Patent Description:
Today's Radio Frequency (RF) transceiver Integrated Circuits (ICs) with integrated radiating elements such as antennae or launchers require testing in production. This testing can include testing of the internal die and testing of the antennae/launchers themselves, as well as the properties of the package that can influence the performance of the antennae/launchers (such as the "artificial dielectric" which is required to achieve the required directional characteristic of the antennae/launchers).

Normally this test can only be done by an external loopback path from transmitter antennae/launchers to receiver antennae/launchers. Tight specification parameters for IC transmit power, transmit and receive antennae/launchers gain and receiver noise figure require this loopback path to be extremely precise, despite the very challenging environmental conditions on production test floors.

In advanced radar transceiver ICs, a recently evolving technology is to integrate transmit and receive antennae into the package (Antennae in Package: AiP). Another technology is to integrate launchers into the package - these launchers are connected via wave guides to external antennae of the package. For such ICs, RF transmitter output power and receiver noise figure are key parameters, but measuring them is extremely difficult because the measurement result depends strongly on a number of conditions such as:.

These dependencies can be mitigated if the RF signals from the IC transmit antennae are fed via an external loopback path to the IC receive antennae, so that the IC can measure the received signal amplitude and phase.

The loopback path can be realized using a waveguide. The parameters of the waveguide such as wall thickness, surface roughness and alignment accuracy to the AUT largely influence the measurements. Therefore, it is desirable to have a standardized loopback path device to be used for all cases where RF parameters need to be precisely measured including, for example:.

A solution for a standardized loopback path device at the various sites, combining high precision, high sensitivity to antenna or launcher misalignments, but low sensitivity to misalignments of this loopback path device, is currently not available.

<CIT> describes an over-the-air (OTA) wireless test system that includes a container, a machine plate disposed on the container, a supporter disposed on the machine plate, a load board disposed on the supporter, a socket disposed on the load board, a device under test (DUT) installed in the socket, and a wave-guiding feature in the socket and the load board configured to pass and guide electromagnetic waves to and/or from an antenna structure of the DUT. The wave-guiding feature comprises a wave-guiding channel in the socket defined by a plurality of pogo pins surrounding the antenna structure of the DUT. The wave-guiding feature may further comprise a radiation passage in the load board defined by rows of via fence extending through an entire thickness of the load board.

<CIT> describes a wireless test system that includes a load board having an upper surface and a lower surface. The load board has a testing antenna disposed on the load board. A socket for receiving a device under test, DUT, having an antenna structure therein is disposed on the upper surface of the load board. The antenna structure is aligned with the testing antenna. The wireless test system further includes a handler for picking up and delivering the DUT to the socket. The handler has a clamp for holding and pressing the DUT. The clamp is grounded during testing and functions as a ground reflector that reflects and reverses radiation pattern of the DUT from an upward direction to a downward direction toward the testing antenna.

<CIT> describes a method for testing a device under test (DUT). The method comprises communicating signals wirelessly from a first plurality of patch antennae disposed on a top surface of the DUT to a second plurality of patch antennae disposed on a printed circuited within a handler device, wherein the handler device is operable to place the DUT in a socket of a tester system, and wherein the tester system comprises the handler device and a test fixture. The method further comprises communicating the signals captured by the second plurality of patch antennae using microstrip transmission lines to a patch antenna on the printed circuit board, wherein a first waveguide is mounted to the patch antenna using a first waveguide flange, and wherein the first waveguide flange is coupled to a first end of the first waveguide.

<CIT> describes conduit structures for guiding extremely high frequency (EHF) signals. The conduit structures can include EHF containment channels that define EHF signal pathways through which EHF signal energy is directed. The conduit structures can minimize or eliminate crosstalk among adjacent paths within a device and across devices. Launch structures that interface with waveguides are also described. Launch structures can control the EHF interface impedance between a contactless communication unit and the waveguide. The waveguide structures are designed to provide maximum bandwidth with minimal jitter over a desired distance.

Aspects of the present disclosure are set out in the accompanying independent and dependent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as appropriate and not merely as explicitly set out in the claims.

According to an aspect of the present disclosure, a test apparatus is provided according to claim <NUM>.

According to another aspect of the present disclosure, there is provided a method according to claim <NUM>.

The provision of the dielectric portion can provide a matched interface for the electromagnetic coupling of the plurality of waveguide openings of the plunger to the plurality of radiating elements of the device.

The radiating elements of the semiconductor device may, for instance, comprise antennae and/or launchers. The transmit elements may accordingly, for instance, comprise transmit antennae or transmit launchers, while the receive elements may accordingly, for instance, comprise receive antennae or receive launchers.

The dielectric portion may have a thickness, measured between the plurality of external radiating elements located at a surface of the device and the plurality of waveguide openings of the plunger, which is substantially equal to λ/<NUM>, where λ is a wavelength of the electromagnetic radiation in the dielectric portion. The thickness may be chosen in according with the intended wavelength of the electromagnetic radiation to be used during the test process, allowing for good matching and coupling between the plurality of waveguide openings of the plunger to the plurality of external radiating elements of the device.

The dielectric portion may have a curved surface for coupling electromagnetic radiation transmitted by a plurality of transmit elements of the device to an opening of the plurality of waveguide openings of the plunger.

The curved surface may be concave or convex when viewed from the waveguide(s) of the plunger.

The dielectric portion may be further configured to provide a seal to prevent airflow across the external radiating elements of the semiconductor device and/or the plurality of waveguide openings of the plunger during testing of the semiconductor device using said test apparatus. Accordingly, the dielectric portion can also can act as a seal for preventing air flow in the vicinity of the radiating elements of the semiconductor device and the waveguide openings of the plunger during the testing process, which may otherwise introduce errors into the test results.

The test apparatus may further comprise an attenuating portion located in at least one of the at least one waveguide of the plunger. This can allow a receive element of the semiconductor device to receive electromagnetic radiation from one (or more) transmit element(s) of the semiconductor device, bearing in mind that the transmit power of the transmit element may exceed the power receivable by a single receive element.

At least one of the waveguides may be configured to route electromagnetic radiation transmitted by one of said transmit elements of the device to a plurality of receive elements of the device. This can allow the plurality of receive elements collectively to be used for testing the transmit element (and vice versa), bearing in mind that the transmit power of the transmit element may exceed the power receivable by a single receive element.

The dielectric portion may comprise a high-density polyethylene (HDPE) or a polycarbonate (e.g. Makrolon), Peek or a ceramic material.

According to a further aspect of the present disclosure, there is provided an apparatus according to claim <NUM>.

The semiconductor device may include a semiconductor die located in a package. The surface of the device at which the plurality of radiating elements are located may be an external surface of the package.

wherein the surface of the device at which the plurality of radiating elements are located is a surface of the carrier.

The method may further include using the plunger to press the semiconductor device into a socket. Accordingly, the test method may be performed as part of an assembly process.

Embodiments of this disclosure will be described hereinafter, by way of example only, with reference to the accompanying drawings in which like reference signs relate to like elements and in which:.

Embodiments of this disclosure are described in the following with reference to the accompanying drawings.

<FIG> each show an example of a semiconductor device <NUM>.

The device <NUM> in <FIG> includes a semiconductor die <NUM> forms an integrated circuit, which may typically include circuitry for transmitting/receiving and processing mm-wave signals for use in, for example, the automotive industry. The semiconductor die <NUM> may be encapsulated in an encapsulant <NUM>. In this example, the semiconductor die <NUM> is mounted on a surface of a carrier <NUM>, such as a printed circuit board. The carrier <NUM> may comprise, for example, RO3003 or RF4 materials. Electrical connections <NUM> between the carrier and the semiconductor die <NUM> may be formed using, for example, an array of solder balls as shown in <FIG>, although other kinds of connections of the kind known in the art may be used also.

The semiconductor device <NUM> in each of <FIG> includes a plurality of radiating elements located at a surface of the device <NUM>. In the example of <FIG>, the radiating elements are provided in the form of strip line antennae <NUM>, <NUM> comprising metallic strips located on the surface of the carrier <NUM>. The radiating elements include a plurality of transmit elements <NUM> and a plurality of receive elements <NUM>. Electrical connections <NUM> between the radiating elements and the semiconductor die <NUM> may be formed by a combination of metal tracks located on the surface of the carrier <NUM> and the aforementioned electrical connections <NUM>.

The semiconductor device <NUM> shown in <FIG> is similar to that shown in <FIG>, except that the device <NUM> further includes a waveguide antenna <NUM> which may be located on top of the semiconductor die <NUM> and the carrier <NUM>. The waveguide antenna <NUM> includes channels <NUM> for guiding electromagnetic radiation to/from the plurality of receive elements <NUM> and the plurality of transmit elements <NUM>. These channels may terminate in an array of transmit elements <NUM> and an array of receive elements <NUM>. In the example of <FIG>, it is the transmit elements <NUM> and the receive elements <NUM> that form the radiating elements of the semiconductor device <NUM>. The arrangement of the strip line antennae and radiating elements in the example of <FIG> may be referred to as an external launcher.

The semiconductor device <NUM> shown in <FIG> is similar to that shown in <FIG>, except that the device <NUM> in <FIG> does not include strip line antennae as described above in relation to <FIG>. Instead, the device <NUM> in <FIG> includes transmit elements <NUM> for transmitting mm-wave signals and receive elements <NUM> for transmitting mm-wave signals which are provided inside the encapsulant <NUM>. Electrical connections <NUM> between the semiconductor die <NUM> and the transmit elements <NUM> and receive elements <NUM> may pass through the encapsulant (and/or via the electrical connections <NUM>). Like the semiconductor device <NUM> of <FIG>, the semiconductor device <NUM> in <FIG> includes a waveguide antenna <NUM>, which may be located on top of the semiconductor die <NUM> and the carrier <NUM>. The waveguide antenna <NUM> includes channels <NUM> for guiding electromagnetic radiation to/from the receive elements <NUM> and the transmit elements <NUM>. Again, these channels may terminate in an array of transmit elements <NUM> and an array of receive elements <NUM>. In the example of <FIG>, it is again the transmit elements <NUM> and the receive elements <NUM> that form the radiating elements of the semiconductor device <NUM>. The arrangement of the transmit elements <NUM> and receive <NUM> and radiating elements <NUM>, <NUM> in the example of <FIG> may be referred to as an integrated launcher.

In <FIG>, the encapsulant <NUM> may be considered to form a package of the semiconductor die <NUM>. In <FIG>, the encapsulant <NUM> and/or the waveguide antenna <NUM> may be considered to form a package of the semiconductor die <NUM>.

As noted previously, to test a semiconductor device <NUM> of the kind shown in <FIG>, it is necessary to test the operation of the radiating elements. The test may involve placing a plunger against the surface of the semiconductor device <NUM>, the plunger having waveguide openings for coupling electromagnetically to the radiating elements of the device <NUM>. The plunger may include a loopback path, allowing the receive elements of the device <NUM> to receive electromagnetic radiation (mm-wave signals) transmitted by the transmit elements of the device <NUM>. A solution for a standardized loopback path device at the various sites, combining high precision, high sensitivity to radiating element misalignments, but low sensitivity to misalignments of this loopback path device, is currently not available.

Test apparatuses according to embodiments of this disclosure will now be described in relation to <FIG>.

<FIG> shows a semiconductor device <NUM> which shares features of the kind described above in relation to <FIG>. The device <NUM> includes a semiconductor die <NUM> which may be provided in an encapsulant <NUM>. The device <NUM> also includes a waveguide antenna <NUM>, which includes a plurality of radiating elements arranged in an array, which includes transmit elements <NUM> and receive elements <NUM> provided at a surface of the device <NUM>. The semiconductor die <NUM>, encapsulant <NUM> and waveguide antenna <NUM> may be mounted on a surface of a carrier <NUM>, as explained in relation to <FIG>.

The test apparatus in this embodiment includes a dielectric portion <NUM>, which may be included in a plunger. The dielectric portion <NUM> is shown in <FIG> with the remainder of the plunger omitted (further details of the plunger will be described below with reference to <FIG>. The dielectric portion <NUM> may be provided in the form of a layer. The dielectric portion <NUM> has a surface (the underside of the dielectric portion <NUM> shown in <FIG>), which may be placed against the surface of the semiconductor device <NUM> that includes the radiating elements of the device <NUM>. The surface to be placed against the surface of the semiconductor device <NUM> that includes the radiating elements of the device <NUM> may, for example, be substantially planar, although it also may in general be profiled to match the profile of the surface of the semiconductor device <NUM>. The dielectric portion <NUM> may also have a surface <NUM> (which is generally an opposite surface of the dielectric portion <NUM> to the surface which is to be placed against the semiconductor device <NUM>). Further features of the plunger (such as the plurality of waveguide openings of the plunger, to be described below) may be located against the surface <NUM> of the dielectric portion <NUM>.

Turning to <FIG>, the plunger may further include a block <NUM>, which can house a plurality of waveguide openings <NUM> and waveguides <NUM>. The block may comprise a metal (e.g. copper). The waveguide openings <NUM> are arranged in locations that correspond to the locations of the transmit elements <NUM> and receive elements <NUM> provided at the surface of the device <NUM>, thereby allowing the plurality of waveguide openings <NUM> to couple electromagnetically to corresponding transmit/receive elements of the plurality of radiating elements located at the surface of the device.

The waveguides <NUM> may comprise channels that extend into the plunger from the waveguide openings <NUM>, so as to route electromagnetic radiation transmitted by the transmit elements <NUM> to the receive elements <NUM> in a loopback arrangement as explained previously. The waveguides may be filled with a dielectric. Each waveguide may extend between at least one of the transmit elements <NUM> and at least one of the receive elements <NUM>. As shown in <FIG>, the waveguide openings <NUM> may taper outwardly as the extend away from the waveguides <NUM>, so as to provide a better matching to the electromagnetic field in the dielectric portion <NUM>.

The dielectric portion <NUM> is configured to provide a matched interface for the electromagnetic coupling of the plurality of waveguide openings <NUM> of the plunger to the plurality of radiating elements (the transmit elements <NUM> and the receive elements <NUM>) of the semiconductor device <NUM>. To this end, the material of the dielectric portion <NUM> may be chosen according to the specific application and the electromagnetic wavelengths to be used in the testing of the device <NUM>. Suitable materials for the dielectric portion <NUM> include high-density polyethylene (HDPE) and a polycarbonate such as Makrolon or Peek, or a ceramic material. The thickness T (see <FIG>) of the dielectric portion <NUM> may also be chosen so as to enhance the matched interface between the plurality of waveguide openings <NUM> of the plunger and the plurality of radiating elements (the transmit elements <NUM> and the receive elements <NUM>) of the semiconductor device <NUM>. In particular, the thickness T of the dielectric portion <NUM> may be chosen to be λ/<NUM>, where λ is a wavelength of the electromagnetic radiation to be used (i.e. transmitted by the transmit elements <NUM> and received by the receive elements <NUM>) during the testing of the semiconductor device <NUM>. Note that λ denotes the wavelength of the electromagnetic radiation inside the dielectric portion <NUM>. By way of example only, where the dielectric portion <NUM> comprises HDPE, and considering an example frequency of <NUM>, the thickness T may be chosen to be around <NUM>. In another example, where the dielectric portion <NUM> comprises Makrolon, and again considering an example frequency of <NUM>, the thickness T may be chosen to be around <NUM>.

The dielectric portion <NUM> may also act to provide a seal to prevent unwanted airflow during testing of the semiconductor device <NUM> using the test apparatus. For instance, by placing the dielectric portion <NUM> against the surface of the semiconductor device <NUM> including the radiating elements of the device <NUM>, the dielectric portion <NUM> may seal off the surface of the semiconductor device <NUM> including the radiating elements. This can prevent airflow around the radiating elements of the device <NUM>, which may otherwise affect the results of the test. It is also noted that the dielectric portion <NUM> may seal off the waveguide openings <NUM> of the plunger, again to prevent unwanted airflow.

Although the embodiment of <FIG> is described in relation to a semiconductor device which, as described in <FIG>, has a waveguide antenna <NUM>, it is envisaged that the plunger may also be used with a semiconductor device <NUM> of the kind shown in <FIG>. In such cases, the waveguide openings <NUM> of the plunger may couple directly with the strip line antennae <NUM>, <NUM> on the surface of the carrier <NUM>, which form the radiating elements of the device <NUM> in such embodiments.

In some embodiments, the dielectric portion may include a curved surface, for coupling electromagnetic radiation transmitted by a plurality of transmit elements <NUM> of the device <NUM> to a waveguide opening <NUM> of said plurality of waveguide openings of the plunger. Conversely, the curved surface may also allow coupling of electromagnetic radiation transmitted by one of the waveguide openings <NUM> to a plurality of receive elements <NUM> of the device. An example of such an embodiment is shown in <FIG>. As with <FIG>, the dielectric portion <NUM> in <FIG> is shown with the remainder of the plunger omitted so as to reveal the configuration of the curved surface <NUM>. The curved surface may act as a lens antenna. The curved surface <NUM> in this embodiment is concave when viewed from the waveguide(s) of the plunger. In other embodiments, curved surface <NUM> may be convex when viewed from the waveguide(s) of the plunger. The curved surface <NUM> may, for instance, have a substantially cylindrical profile as shown in <FIG>, however other surface profiles are envisaged. The curvature of the curved surface <NUM> may be chosen according to the dielectric constant of the material used to form the dielectric portion <NUM>. The space created between the curved surface <NUM> and the waveguide openings <NUM> of the plunger may be filled with another dielectric, such as air.

In some embodiments, at least one of the waveguides of the plunger may be configured to route electromagnetic radiation transmitted by one of the transmit elements <NUM> of the device <NUM> to a plurality of receive elements <NUM> of the device <NUM>. Examples of this will be described below in relation to the embodiments of <FIG> and <FIG>.

<FIG> schematically illustrates the coupling of a plurality of waveguide openings <NUM> of a plunger according to an embodiment of this disclosure to a plurality of transmit elements <NUM> (Tx1, Tx2, Tx3) and a plurality of receive elements <NUM> (Rx1, Rx2, Rx3, Rx4) of a semiconductor device <NUM>. In this embodiment, waveguide <NUM> of the plunger routes electromagnetic radiation from transmit element Tx1 to receive element Rx4, while waveguide <NUM> routes electromagnetic radiation from transmit element Tx2 to receive element Rx3. Accordingly, waveguides <NUM>, <NUM> each route electromagnetic radiation between a single transmit element <NUM> and a single receive element <NUM>. However, as can be seen in <FIG>, waveguide <NUM> in this embodiment routes electromagnetic radiation from transmit element Tx3 to receive element Rx1 and also to receive element Rx2. This kind of arrangement can allow a plurality of receive elements <NUM> collectively to be used for testing the transmit element <NUM> (and vice versa) of the device <NUM>, bearing in mind that the transmit power of the transmit element <NUM> may exceed the power receivable by a single receive element <NUM>.

In order to implement the routing of electromagnetic radiation from a transmit element <NUM> of the device <NUM> to more than one receive element <NUM> of the device <NUM>, the waveguide used (e.g. see waveguide <NUM> in <FIG>) may include a plurality of branches. In <FIG> for instance, the waveguide <NUM> in <FIG> includes a first branch 64A for conveying electromagnetic radiation transmitted by transmit element Tx1, a second branch 64B for routing the electromagnetic radiation to receive element Rx1 and a third branch 64C for routing the electromagnetic radiation to receive element Rx2. The first branch 64A of waveguide <NUM> in this embodiment thus splits into two separate branches 64B, 64C at location <NUM>.

<FIG> show an example construction of a plunger having at least one branched waveguide of the kind described above in relation to <FIG>. <FIG> is a 3D view, while <FIG> is a plan view, viewed from above the surface to the semiconductor device <NUM> having the radiating elements. The semiconductor device <NUM> itself is also shown in <FIG>.

The arrangement of the waveguides <NUM>, <NUM>, <NUM> in <FIG> is similar to that shown in <FIG>, with the waveguides <NUM>, <NUM> each routing electromagnetic radiation between a single transmit element <NUM> and a single receive element <NUM> and the waveguide <NUM> including multiple branches for routing of electromagnetic radiation from a transmit element <NUM> of the device <NUM> to more than one receive element <NUM> of the device <NUM>. <FIG> also include a cut out <NUM> in the block <NUM>, which may be receiving a nozzle of the plunger, for use in moving the plunger into position during the test procedure. As can be seen in <FIG>, the waveguides <NUM>, <NUM>, <NUM> can be shaped around the cut out <NUM> - for instance the branches of the waveguide <NUM> split on one side of the cut out, and the branches leading to the receive elements <NUM> of the device <NUM> may extend through the plunger on opposite sides of the cut out <NUM>.

<FIG> show an example construction of a plunger having at least one branched waveguide of the kind described above in relation to <FIG>. <FIG> is a cross section, while <FIG> is a plan view, viewed from above the surface to the semiconductor device <NUM> having the radiating elements. The semiconductor device <NUM> itself is also shown in <FIG>.

The arrangement of the waveguides <NUM>, <NUM>, <NUM> in <FIG> is again similar to that shown in <FIG>, with the waveguides <NUM>, <NUM> each routing electromagnetic radiation between a single transmit element <NUM> and a single receive element <NUM> and the waveguide <NUM> including multiple branches for routing of electromagnetic radiation from a transmit element <NUM> of the device <NUM> to more than one receive element <NUM> of the device <NUM>.

In this embodiment, the routing of the waveguides is implemented using a printed circuit board (PCB) <NUM> located on the plunger. The PCB <NUM> includes patterned metal features <NUM> that are shaped and configured so as to route the electromagnetic radiation in the waveguides. It is envisaged that a PCB <NUM> of the kind described here in relation to <FIG> may also be used to implement routing in a plunger that does not include branched waveguides such as waveguide <NUM>, but in which each waveguide routes the electromagnetic radiation from a single transmit element <NUM> to a single receive elements <NUM> of the device <NUM>.

In some embodiments one or more of the waveguides may be provided with an attenuating portion for attenuating the electromagnetic radiation transmitted by the transmit element/elements <NUM> of the semiconductor device <NUM> before it is looped back around to the receive element/elements <NUM> of the device <NUM>. An example of this is shown in the embodiment of <FIG>. As shown in <FIG>, the attenuating portion <NUM> may be located inside waveguide <NUM>. Suitable materials for the attenuating portion include an absorbing foam such as those available from ECOSORB. The attenuating portion <NUM> can allow a receive element <NUM> of the semiconductor device <NUM> to receive electromagnetic radiation from one (or more) transmit elements <NUM> of the semiconductor device <NUM>, bearing in mind that the transmit power of the transmit element/elements <NUM> may exceed the power receivable by a single receive element <NUM>.

In a standard way of measuring the RF parameters of a mmWave device, the RF parameters of a mmWave integrated circuit are directly measured during validation, production testing, at the customer validation site, and in repair workshops in the field. This generally requires mmWave test lab equipment, standardized measurement antennae and several measurement parameters to be standardized. Despite the high effort and costs for such measurements, the result is often too imprecise and not sufficiently repeatable and reproducible. Accordingly, this procedure does not fit for precise mmWave radar measurements in varying environments, with varying measurement equipment and several other parameters, which are hard to standardize.

As explained previously, testing of a mmWave device can be performed by forming a loopback path, in which the electromagnetic radiation transmitted by transmit elements of a device may be looped back to the receive elements of the device. Testing of this kind may involve the following steps.

First, the RF parameters on several integrated circuits may be directly measured in a mmWave RF lab. Then, the RF parameters of these integrated circuits may be determined using an external device containing a loopback path. The RF lab can correlate the RF parameters, measured by the lab equipment, with the RF loopback parameters as measured by the loopback method. The RF loopback parameters, measured under standardized conditions, can then then serve as a reference.

Accordingly, following this approach, what is guaranteed to the customers are the parameters measured by loopback test using a standardized loopback device, not those parameter measured in a mmWave RF lab. In other words, what is guaranteed to the customers is the receive power, and the receive noise level, measured by the integrated circuit when the loopback device is used. What is not guaranteed is transmitter output power or the receiver noise figure.

The loopback device may then be used in all occurrences the RF parameters are needed, for instance in validation, production testing, testing of customer rejects, testing at the customer site and in car repair workshops.

<FIG> schematically illustrates the test setup for testing a semiconductor device of the kind described here, using the loopback approach. The setup includes the test apparatus <NUM>, which may include waveguides having waveguide openings <NUM> for looping the electromagnetic radiation transmitted by the transmit elements <NUM> of the device <NUM> under test to the receive elements <NUM> of the device <NUM>. For simplicity, the device <NUM> illustrated in <FIG> includes a single transmit element <NUM> and a single receive element, while the test apparatus includes two respective waveguide openings <NUM> and a single, non-branched, waveguide. Nevertheless, it will be appreciated that the principles to be described below apply also to devices <NUM> including more than one transmit element <NUM> and/or receive element <NUM> and to test apparatuses including corresponding waveguide openings <NUM>, as well as to test apparatuses including branched waveguides as explained in relation to <FIG> and <FIG>.

A potential issue with a test setup of the kind shown in <FIG> is that misalignment of the waveguide openings <NUM> of the test apparatus <NUM> with the radiating elements <NUM>, <NUM> of the device <NUM> under test can lead to inaccurate test results. In <FIG>, a lateral misalignment between the transmit element <NUM> of the device <NUM> and the corresponding waveguide opening <NUM> of the test apparatus <NUM> is denoted as Δxtx, while a misalignment between the receive element <NUM> of the device <NUM> and the corresponding waveguide opening <NUM> of the test apparatus <NUM> is denoted as Axrx.

<FIG> illustrates the effects of the misalignments noted above. The vertical axis in <FIG> denotes the coupling factor (in dB) between the transmit element <NUM> of the device <NUM> and the corresponding waveguide opening <NUM> of the test apparatus <NUM> (left hand curve) and the coupling factor between the receive element <NUM> of the device <NUM> and the corresponding waveguide opening <NUM> of the test apparatus <NUM> (right hand curve). The coupling factor is shown as a function of misalignment Δxtx (left hand curve) and misalignment Δxrx (right hand curve). Note that for each radiating element <NUM>, <NUM>, it is assumed the peak coupling factor occurs when Δxtx and Δxrx are zero, i.e. when each radiating element <NUM>, <NUM> and its corresponding waveguide opening <NUM> are positioned directly opposite each other, without any lateral misalignment (represented by Tx1 and Rx1 in <FIG>). As can be seen from the curves in <FIG>, the coupling factor decreases with increasing positive or negative misalignment Δxtx, Δxrx.

It will be appreciated that, assuming the fixed lateral spacing between the transmit element <NUM> and the receive element <NUM> is equal to the fixed lateral distance between the corresponding waveguide opening <NUM> of the test apparatus <NUM>, a lateral misalignment between transmit element <NUM> and its corresponding waveguide opening <NUM> of the test apparatus <NUM> results in a corresponding lateral misalignment between receive element <NUM> and it corresponding waveguide opening <NUM> of the test apparatus <NUM>. That is to say, in <FIG>, in general Δxtx = Δxrx.

Tx2 and Rx2 in <FIG> correspond to a small misalignment, while Tx3 and Rx3 correspond to a larger misalignment. The coupling factor for each radiating element/waveguide opening pair at Tx2, Rx2 is reduced compared to Tx1, Rx1 (Δxtx = Δxrx = <NUM>) owing to the small misalignment of the radiating elements/waveguide openings, while the coupling factor for each radiating element/waveguide opening pair at Tx3, Rx3 is further reduced compared to Tx2, Rx2 owing to the larger misalignment of the radiating elements/waveguide openings.

In accordance with embodiments of this disclosure, the lateral spacing between the waveguide openings <NUM> of the test apparatus <NUM> is intentionally made larger than, or smaller than the lateral spacing between the corresponding transmit elements <NUM> and receive elements <NUM> of the device <NUM>. As will now be explained in relation to <FIG>, this automatically (and counterintuitively) leads to misalignments between the transmit and receive elements <NUM>, <NUM> of the device <NUM> under test and the corresponding waveguide openings <NUM> of the test apparatus <NUM>.

Like <FIG> shows the coupling factor between the transmit element <NUM> of a device <NUM> under test and its corresponding waveguide opening <NUM> of the test apparatus <NUM> (left hand curve), and the coupling factor between the receive element <NUM> of a device <NUM> under test and its corresponding waveguide opening <NUM> of the test apparatus <NUM> (right hand curve). In this embodiment, the lateral spacing between the waveguide openings <NUM> of the test apparatus <NUM> is intentionally smaller than the lateral spacing between the transmit and receive elements <NUM>, <NUM>. When the test apparatus <NUM> is moved into its measurement position, there will therefore always be at least some misalignment between either the transmit element <NUM> and its corresponding waveguide opening <NUM> and/or the receive element <NUM> and its corresponding waveguide opening <NUM>.

In <FIG>, three example positions of the test apparatus <NUM> are illustrated: Tx1, Rx1; Tx2, Rx2; and Tx3, Rx3.

Note that position Tx2, Rx2 gives rise to an equal amount of misalignment (although in the opposite direction) between the transmit element <NUM> and its corresponding waveguide opening <NUM> of the test apparatus <NUM> and between the receive element <NUM> and its corresponding waveguide opening <NUM>. That is to say that for position Tx2, Rx2, (Δxtx = - Δxrx).

At position Tx1, Rx1, the misalignment between the transmit element <NUM> and its corresponding waveguide opening <NUM> is reduced relative to position Tx2, Rx2, whereas the misalignment between the receive element <NUM> and its corresponding waveguide opening <NUM> is increased. Similarly, at position Tx3, Rx3, the misalignment between the transmit element <NUM> and its corresponding waveguide opening <NUM> is increased relative to position Tx2, Rx2, whereas the misalignment between the receive element <NUM> and its corresponding waveguide opening <NUM> is reduced. Accordingly, it will be appreciated that there is a tendency for reductions in the overall coupling factor resulting from misalignments relative to position Tx2, Rx2 to cancel out (bearing in mind that the loopback test arrangement requires the electromagnetic radiation passing through the waveguide of the test apparatus <NUM> to be coupled twice between the device <NUM> and the test apparatus <NUM>: once at the transmit element <NUM> and once at the receive element <NUM>). Because of this, the aforementioned intentional reduction in the lateral spacing between the waveguide openings <NUM> of the test apparatus <NUM> has led to an overall reduction in sensitivity of coupling factor to misalignments (relative to position Tx2, Rx2) between the waveguide openings <NUM> of the test apparatus <NUM> and those of the device <NUM> under test. To a first order approximation, the overall coupling factors Tx1+Rx1 ≈ Tx2+Rx2 ≈ Tx3+Rx3. This can improve the accuracy and repeatability of tests on semiconductor devices <NUM> of the kind described herein, using a test apparatus <NUM> having a loop back waveguide arrangement.

It will be appreciated, for example with reference to <FIG>, that although in the embodiment of <FIG> the lateral spacing between the waveguide openings <NUM> is smaller than the lateral spacing between the transmit and receive elements <NUM>, <NUM>, similar benefits can arise in cases in which the lateral spacing between the waveguide opening <NUM> is larger than the lateral spacing between the transmit and receive elements <NUM>, <NUM>. In <FIG>, three example positions of the test apparatus <NUM> are again illustrated, although this time for a test apparatus <NUM> in which the lateral spacing between the waveguide openings <NUM> is larger than the lateral spacing between the transmit and receive elements <NUM>, <NUM>: Tx1, Rx1; Tx2, Rx2; and Tx3, Rx3.

Again position Tx2, Rx2 gives rise to an equal amount of misalignment (although in the opposite direction) between the transmit element <NUM> and its corresponding waveguide opening <NUM> of the test apparatus <NUM> and between the receive element <NUM> and its corresponding waveguide opening <NUM>. That is to say that for position Tx2, Rx2, (-Δxtx = Δxrx).

In <FIG>, at position Tx1, Rx1, the misalignment between the transmit element <NUM> and its corresponding waveguide opening <NUM> is again reduced relative to position Tx2, Rx2, whereas the misalignment between the receive element <NUM> and its corresponding waveguide opening <NUM> is again increased. Similarly, at position Tx3, Rx3, the misalignment between the transmit element <NUM> and its corresponding waveguide opening <NUM> is again increased relative to position Tx2, Rx2, whereas the misalignment between the receive element <NUM> and its corresponding waveguide opening <NUM> is again reduced. Accordingly, it will again be appreciated that there is a tendency for reductions in the overall coupling factor resulting from misalignments relative to position Tx2, Rx2 to cancel out. Because of this, the aforementioned intentional increase in the lateral spacing between the waveguide openings <NUM> of the test apparatus <NUM> has led to an overall reduction in sensitivity of coupling factor to misalignments (relative to position Tx2, Rx2) between the waveguide openings <NUM> of the test apparatus <NUM> and those of the device <NUM> under test. Again, to a first order approximation, the overall coupling factors Tx1+Rx1 ≈ Tx2+Rx2 ≈ Tx3+Rx3. As with the embodiment of <FIG>, this can therefore improve the accuracy and repeatability of tests on semiconductor devices <NUM> of the kind described herein, using a test apparatus <NUM> having a loop back waveguide arrangement.

The lateral spacing between the waveguide openings <NUM> of the test apparatus <NUM> may differ from (i.e. larger than or smaller than) the lateral spacing between the transmit and receive elements <NUM>, 24by an amount that may, for instance, be chosen according to the shape (e.g. slope, width etc.) of the coupling factor curves. Typically it is envisaged that the spacing between the waveguide openings <NUM> of the test apparatus <NUM> may larger than, or smaller, than the spacing between the corresponding transmit and receive elements <NUM>, 24of the device <NUM> by at least <NUM>%, or by at least <NUM>%.

According to embodiments of this disclosure, intentional smaller or larger lateral spacing between the waveguide openings may be employed in any test apparatus having:
a test apparatus for testing the semiconductor device, the test apparatus comprising:.

The test apparatus may, for instance, include a test apparatus of the kind described above in relation to any of <FIG>, although it is envisaged that the previously described dielectric portion <NUM> may, or may not be present in such embodiments.

The semiconductor device under test may comprise an integrated circuit and a plurality of external radiating elements located at a surface of the device, the external radiating elements including at least one transmit element and at least one receive element. By way of example, the device under test may be a device <NUM> of the kind described above in relation to any of <FIG>.

Testing of a semiconductor device <NUM> comprising an antenna in package (AiP) or Launcher in Package (LiP) such as those described in relation to <FIG> may generally not simply involve testing the radiating elements of the device <NUM>. The testing may also involve testing any internal antenna of the device <NUM> (for instance the strip line antennae <NUM>, <NUM> shown in <FIG> or the transmit and receive elements <NUM>, <NUM> shown in <FIG>). The testing may also involve the so-called "artificial dielectric" - this are structures which make sure that the transmit and receive elements have the intended directional characteristics.

Temperature cycling, aging and/or production variations/defects may lead to defects which manifest in different ways. In some cases, the position of one of the transmit or receive elements of the device <NUM> may be shifted to a different position to that intended during manufacture. In more frequent cases, the geometrical antenna position may stay the same, but the apparent antenna position (i.e. the effective position according to the antenna directivity) may change. This can lead to the RF properties (e.g. gain, directivity) of the antennae of the device changing, as though the position of the antennae had changed, even though the actual positions of the antennae may remain unchanged. It is desirable that these effects are also accounted for during the loop back test procedure. Although it is desirable that these measurements be insensitive to misalignments of the test apparatus, it is also desired that they be sensitive to any changes (real or apparent) of the antennae themselves.

<FIG> shows the coupling factor between the transmit element <NUM> of a device <NUM> under test and its corresponding waveguide opening <NUM> in the test apparatus <NUM>, and the coupling factor between the receive element <NUM> of the device <NUM> and its corresponding waveguide opening <NUM> in the test apparatus <NUM>. In <FIG> it is assumed that the lateral spacing between the waveguide openings <NUM> in the test apparatus <NUM> is smaller than the lateral spacing between the transmit element <NUM> and the receive element <NUM> as described above in relation to <FIG>.

In <FIG>, position Tx, Rx2 is considered to be the "nominal" position, and corresponds to the position Tx2, Rx2 in <FIG>. <FIG> also shows two example deviations from Tx, Rx2, namely Tx, Rx1 and Tx, Rx3. Tx, Rx1 and Tx, Rx3 each correspond to a change in lateral spacing (real or apparent) between the transmit and receive elements <NUM>, 24of the semiconductor device <NUM>. In particular, in the case of Tx, Rx1, the lateral spacing between the transmit and receive elements <NUM>, 24is increased, whereas in the case of Tx, Rx3, the lateral spacing between the transmit and receive elements <NUM>, 24is decreased.

As can be seen, compared to Tx2, Rx2, a slight increase of the distance (Tx, Rx3) leads to worse coupling at the receive element <NUM>. Likewise, a slight decrease of the distance (Tx, Rx1) leads to better coupling at the receive element <NUM>. Hence, the change of the overall loopback transmission factor, Tx+Rx1, Tx+Rx3 versus the standard case Tx+Rx2, is large in this example (Tx+Rx1>>Tx+Rx2; Tx+Rx3«Tx+Rx2). Accordingly, it will be appreciated that the sensitivity of the test procedure to variations in the lateral spacing in the radiating elements of the device <NUM> under test is generally large, notwithstanding the fact that the lateral spacing between the waveguide openings of the test apparatus <NUM> is intentionally different to the "nominal" spacing represented by Tx, Rx2. Although <FIG> has been explained under the assumption that the lateral spacing of the waveguide openings <NUM> is intentionally smaller than the lateral spacing of the transmit and receive elements <NUM>, 24of the device <NUM> under test (as per <FIG>), it will be appreciated that the sensitivity of the test procedure to variations in the lateral spacing in the radiating elements of the device <NUM> under test will also generally be large for lateral spacings of the waveguide openings <NUM> that are intentionally larger than the lateral spacing of the transmit and receive elements <NUM>, <NUM> of the device <NUM> under test (as per <FIG>).

Claim 1:
A test apparatus configured to test a semiconductor device (<NUM>), the semiconductor device comprising an integrated circuit and a plurality of external radiating elements at a surface of the device, the radiating elements including at least one transmit element (<NUM>) and at least one receive element (<NUM>), the test apparatus comprising:
a plunger comprising:
a dielectric portion (<NUM>) having a surface for placing against said surface of the device; and
at least one waveguide (<NUM>, <NUM>, <NUM>, <NUM>), wherein each waveguide extends through the plunger to route electromagnetic radiation transmitted by one of said transmit elements of the device to one or more of the receive elements of the device, wherein each waveguide comprises a plurality of waveguide openings (<NUM>) for coupling electromagnetically to corresponding radiating elements of the plurality of radiating elements located at the surface of the device,
wherein the dielectric portion is configured to provide a matched interface for said electromagnetic coupling of the plurality of waveguide openings of the plunger to the plurality of radiating elements of the device; characterised in that at least one of the waveguides is configured to route electromagnetic radiation transmitted by one of said transmit elements of the device to a plurality of receive elements of the device, wherein said waveguide comprises: a first branch (64A) for conveying electromagnetic radiation transmitted by said transmit element; and at least two further branches (64B, 64C) coupled to the first branch for routing said electromagnetic radiation to said plurality of receive elements.