Patent Description:
In order to properly move and load a wafer, the wafer is usually placed in a probing machine during test procedures and tested by a test head. Generally speaking, the test head may have many probe cards which are electrically connected to a load board, and then the load board is electrically connected to the wafer. Traditionally, the load board does not directly contact the wafer. For example, the load board should be connected to a pogo tower, and then the pogo tower contacts the wafer. Since the pogo tower and the load board need to be placed between the test head and the probing machine, it is obvious that the test head will be away from the probing machine. In addition, because there is the pogo tower disposed between the load board and the wafer, which makes the signal transmission path much longer, and there will be more interference and greater signal attenuation.

To solve the above-mentioned problem of long signal transmission paths, there are some new probing machines that allow the load board to contact the wafer. This connection means between the load board and the wafer is called "direct docking". Since the load board and the wafer are direct docking, there is no need for the pogo tower, which can make the signal transmission path shorter, so it is gradually being adopted by the industry. However, for the traditional probing machine, there is currently no way to remove the pogo tower and switch to the direct docking mode. One reason is that the traditional load board is locked to the test head in the first place, and the pogo tower is also locked to the probing machine. While testing the wafer traditionally, the test head and the probing machine are fixed together by mechanical means to fix the relative position of the load board and the pogo tower, and then the load board can be electrically connected to the wafer through the pogo tower. However, the traditional probing machine is designed to have the pogo tower, and the load board and the wafer are not close to each other. In other words, even though the pogo tower is removed, the load board is still away from the wafer by a considerable distance. And, if the load board is still locked to the test head, there is a problem that the load board cannot touch the wafer for sure. Accordingly, the industry needs a new method for connecting the test head, so that the test head and the probing machine can be adjusted to operate in the direct docking mode.

<CIT> discloses a traditional tester with direct docking using a load board, and a test fixture, where the load board is accommodated, disposed on the test head. <CIT> and <CIT> also disclose traditional testers.

The present invention provides a test head connection method, which can be used to connect a test head to a probing machine. In the method, the load board is set on the probing machine instead of the test head, and when the test head contacts the load board, the load board can be sucked tightly by the vacuum function of the test head to increase the stability between the test head and the probing machine.

The present invention discloses a test head connection method comprising the following steps: disposing a load board and a test fixture between the test head and a probing machine; activating a vacuum function of the test head; moving the test head to align the test fixture; moving the test head until touching the load board in the test fixture; fixing the test head and the test fixture by at least one engaging member. Wherein the test fixture is disposed in the probing machine, the test fixture is used to accommodate the load board, and the load board is configured to connect a wafer by direct probing.

In some embodiments, the test fixture defines a first upper surface, the first upper surface defines a first accommodating space, and the first accommodating space may be used for accommodating the load board. When the load board is accommodated in the first accommodating space, the load board and the first upper surface may form a coplanar surface. Besides, the test head connection method may further comprise: providing a fixing plate detachably locked to the probing machine. Wherein a second upper surface of the fixing plate defines a second accommodating space, and the second accommodating space may be used for accommodating the test fixture. In addition, the first upper surface and the second upper surface are not coplanar, and the test fixture is detachably locked in the second accommodating space of the fixing plate.

In some embodiments, the load board may be detachably locked in the first accommodating space. Besides, in the step of moving the test head to align the test fixture may further comprise: providing an alignment member, disposed on the test fixture, to guide the test head to align with the test fixture. In addition, the test head may contact an upper surface of the load board, and the test fixture may contact a lower surface of the load board. Moreover, the upper surface of the load board defines at least a vacuum area, and the vacuum area may be surrounded by a metal strip.

Based on the above, the test head connection method provided by the present invention can be used to connect the test head to the probing machine, and the vacuum function of the test head can be used to suck the load board tightly, so that the load board can be pressed toward the test head more efficiently. In addition, since the load board is arranged in the probing machine, the stability between the test head and the probing machine can also be increased.

The features, objections, and functions of the present invention are further disclosed below. However, it is only a few of the possible embodiments of the present invention, and the scope of the present invention is not limited thereto; that is, the equivalent changes and modifications done in accordance with the claims of the present invention will remain the subject of the present invention. Without departing from the scope of the invention, it should be considered as further enablement of the invention.

Please refer to <FIG> is a schematic diagram of a test head and a probing machine in accordance with an embodiment of the present invention. As shown in <FIG>, the test head connection method of the present invention can be used to connect the test head <NUM> to the probing machine <NUM>. The probing machine <NUM> can be provided with a wafer to be tested (not shown in the figures), and the test head <NUM> can be electrically connected to the wafer via a load board (not shown in <FIG>). In order to show the structure and components between the test head <NUM> and the probing machine <NUM>, <FIG> illustrates that the test head <NUM> is slightly away from the probing machine <NUM>. It can be seen that the test head <NUM> is above the probing machine <NUM>, and the test head <NUM> has not been connected to the probing machine <NUM>. In practice, the test head <NUM> can also be connected with a robotic arm or crane (not shown in the figures), which can allow the test head <NUM> to move, tilt, or flip in any directions. For example, the robotic arm or crane can allow the test head <NUM> to vertically approach or move away from the probing machine <NUM>, the robotic arm or crane and can also rotate the test head <NUM> when the internal component of the test head <NUM> needs adjustment. Of course, it is also possible for the robotic arm or crane to move the test head <NUM> horizontally to other positions, which is not limited in this embodiment. The structure and operation mode of the test head <NUM> and the probing machine <NUM> will be described below respectively.

Please refer to <FIG>, <FIG> and <FIG> together, <FIG> is a perspective view of the test head in accordance with an embodiment of the present invention, and <FIG> is a perspective view from another angle of the test head in accordance with an embodiment of the present invention. As shown in the figures, the test head <NUM> may has a housing <NUM> and a base body <NUM> protruding from the housing <NUM> in appearance. In one example, the housing <NUM> may define a bottom surface 10a, and the base body <NUM> may also define a test surface 12a. Both the bottom surface 10a and the test surface 12a face the probing machine <NUM> in <FIG>. The base body <NUM> is approximately cube-shaped, and the width W2 of the base body <NUM>, in the same axial direction, is slightly narrower than the width W1 of the housing <NUM>. The present embodiment does not limit the numerical or proportional value between the width W1 and the width W2. Since the base body <NUM> protrudes from the bottom surface 10a, persona having ordinary skill in the art can understand that the bottom surface 10a and the test surface 12a will not be coplanar. In one example, the test surface 12a is closer, in <FIG>, to the probing machine <NUM> than the bottom surface 10a. In addition, the housing <NUM> can be provided with various components for the electrical testing and the vacuum function. For example, the housing <NUM> can be provided with multiple probe cards, and each probe card can have more than one probe set. The probe sets can protrude from the test surface 12a through an opening <NUM> on the test surface 12a.

In an example, each opening <NUM> on the test surface 12a does not necessarily correspond to one of the probe cards. For example, there may be only a few probe cards inside the housing <NUM>, so that some openings <NUM> may not have protruding probe sets. Taking the example shown in <FIG> and <FIG>, the openings <NUM> on the test surface 12a can be divided into two rows, and the number of the openings <NUM> in each row is the same. This embodiment does not limit the number of the openings <NUM> on the test surface 12a. The openings in each row can be surrounded by a sealing strip <NUM> in appearance. In practice, the area surrounded by the sealing strip <NUM> is provided with one or more through holes for vacuum suction, that is, the area surrounded by the sealing strip <NUM> is related to the vacuum function of the test head <NUM>, which will be described later.

In addition, the housing <NUM> may also be provided with an engaging member <NUM>, a fixing member <NUM>, and an alignment member <NUM>. To understand how the engaging member <NUM>, the fixing member <NUM>, and the alignment member <NUM> are fixed to the probing machine <NUM>, the probing machine <NUM> shown in <FIG> will be used for description. Please refer to <FIG>, <FIG> and <FIG> together, <FIG> is a perspective view of the probing machine in accordance with an embodiment of the present invention. As shown in the figures, the probing machine <NUM> may comprise a housing <NUM>, and a test fixture <NUM> and a fixing plate <NUM> may be provided on the side of the housing <NUM> adjacent to the test head <NUM>. In one example, the fixing plate <NUM> is first disposed on the housing <NUM>, and the test fixture <NUM> is then fixed to the housing <NUM> by the fixing plate <NUM>. In detail, the test fixture <NUM> is detachably locked to the fixing plate <NUM>. For example, the test fixture <NUM> can be fixed to the fixing plate <NUM> with screws, which is not limited in this embodiment.

In addition, the test fixture <NUM> may be provided with an engaging member <NUM> and an alignment member <NUM>, and the engaging member <NUM> and the engaging member <NUM> may structurally correspond to each other. For example, the engaging member <NUM> may be a slot, the engaging member <NUM> may be a short post which can be slid into the slot to be locked and fixed to each other. In order to assist the engaging member <NUM> to enter the engaging member <NUM>, the alignment member <NUM> and the alignment member <NUM> can be used to align the test head <NUM> and the probing machine <NUM>. As shown in <FIG> and <FIG>, the alignment member <NUM> may be a groove, the alignment member <NUM> may be a column, and the alignment member <NUM> may accommodate the alignment member <NUM>. This embodiment does not limit the shape of the alignment member <NUM> and the shape of the alignment member <NUM>, as long as the shape of the alignment member <NUM> can correspond to the shape of the alignment member <NUM>, it should be in the scope described in this embodiment. Instead of setting the engaging member <NUM> and the alignment member <NUM> shown in <FIG> on the edge of the test fixture <NUM> and facing the test head <NUM> in <FIG>, the engaging member <NUM> and the alignment member <NUM> can be set on the fixing plate <NUM>. In one example, in order to ensure that the engaging member <NUM> and the engaging member <NUM> are fixed together, the user can pull the fixing member <NUM> (such as a handle) on the test head <NUM> to lock the engaging member <NUM> and the engaging member <NUM> and make the test head <NUM> and the probing machine <NUM> approximately fixed in position. For example, the fixing member <NUM> may trigger a blocking structure (not shown in figures) which can prevent the engaging member <NUM> from exiting or detaching from the engaging member <NUM>. This embodiment does not limit the means of the blocking structure.

By the definition of direct docking, the test surface 12a of the test head <NUM> will contact the load board, and the load board will directly dock the wafer. In order to illustrate the above-mentioned direct docking, please refer to <FIG> and <FIG> together. <FIG> is a schematic diagram of a load board in accordance with an embodiment of the present invention. <FIG> is a schematic diagram of the load board and a fixing plate in accordance with an embodiment of the present invention. <FIG> shows that the test fixture <NUM> and the fixing plate <NUM> are separable. As shown in the figures, the test fixture <NUM> has an upper surface 22a (first upper surface), and the upper surface 22a defines an accommodating space <NUM> (first accommodating space). The fixing plate <NUM> is defined with an upper surface 24a (second upper surface), and the center of the upper surface 24a has a recess, and the recess may be defined as an accommodating space <NUM> (second accommodating space). In the example shown in <FIG>, the fixing plate <NUM> may be a hollow frame. The present embodiment does not limit the size of the fixing plate <NUM>, as long as the accommodating space <NUM> can be used for accommodating the test fixture <NUM>.

Except for the aforementioned engaging member <NUM> and the alignment member <NUM>, the test fixture <NUM> has a basin-shaped in appearance. The edge of the basin-shaped test fixture <NUM> can be locked to the fixing plate <NUM>, and the bottom of the basin-shaped test fixture <NUM> can be accommodated in the fixing plate <NUM>. In one example, the test fixture <NUM> is locked to the upper surface 24a, so the edge of the test fixture <NUM> is higher than the bottom of the test fixture <NUM>. That is, the edge of the test fixture <NUM> is closer to the test surface 12a of the test head <NUM> than the bottom of the test fixture <NUM>. In practice, the bottom of the test fixture <NUM> is the upper surface 22a (first upper surface). When the test fixture <NUM> is contained in the fixing plate <NUM>, the upper surface 22a and the upper surface 24a are not coplanar. In addition, the accommodating space <NUM> is a slightly recessed area on the upper surface 22a, and the accommodating space <NUM> can be used to accommodate the load board <NUM>. The accommodating space <NUM> may be integrally formed with the upper surface 22a, or be a part of the upper surface 22a. The size of the load board <NUM> should be smaller than or equal to the accommodating space <NUM>, that is, the load board <NUM> should be able to put into the accommodating space <NUM>.

The upper surface 26a of the load board <NUM> which is adjacent to the test head <NUM> (shown in <FIG>) may have a plurality of pads <NUM> and vacuum areas <NUM>. Similar to the examples shown in <FIG> and <FIG>, the pads <NUM> on the load board <NUM> can also be divided into two rows, and each row of the pads <NUM> is located in one of the vacuum areas <NUM>. In one example, the load board <NUM> is further provided with a metal strip <NUM> on the edge of the upper surface 26a. The metal strip <NUM> can be regarded as a rectangle in appearance and surround both of the vacuum areas <NUM>. The present embodiment does not limit the position and shape of the metal strip <NUM>. For example, the metal strip <NUM> may not be arranged on the edge of the upper surface 26a, but on the edge of each vacuum area <NUM>. In this case, the metal strip <NUM> can be regarded as two rectangles, each rectangle encloses one of the vacuum areas <NUM>. Of course, on the lower side of the load board <NUM> away from the test head <NUM> (for example, the other surface shown in <FIG>) may have a plurality of probes (not shown) for connecting the wafer, and the probe can pass through the upper surface 22a through the slot <NUM> in the test fixture <NUM>, and directly contact the wafer (not shown) disposed below, which will not be rep.

In practice, in addition to the test fixture <NUM> is locked to the fixing plate <NUM>, and the fixing plate <NUM> is fixed to the housing <NUM>, the load board <NUM> will also be pre-locked in the accommodating space <NUM> of the test fixture <NUM>. In one example, when the load board <NUM> is locked in the accommodating space <NUM>, the upper surface 26a of the load board <NUM> can be the same height (coplanar) with the upper surface 22a of the test fixture <NUM>, or the top of the metal strip <NUM> located on the upper surface 26a can be the same height (coplanar) with the upper surface 22a of the test fixture <NUM>, which is not limited in this embodiment. In other words, when the load board <NUM> is locked in the accommodating space <NUM>, at least a part of the load board <NUM> will be coplanar with the upper surface 22a. In addition, when the test head <NUM> and the probing machine <NUM> are approaching to each other, the base body <NUM> of the test head <NUM> is aligned with the test fixture <NUM>, which also represents the openings <NUM> on the test surface 12a can be aligned with the pads <NUM> on the upper surface 26a since the load board <NUM> and the test fixture <NUM> do not move relatively to each other. In practice, the upper surface 26a of the load board <NUM> is used to contact the base body <NUM> of the test head <NUM>, and the surface (for example, the lower side) of the load board <NUM> opposite to the upper surface 26a is used to contact the test fixture <NUM>.

Then, when the test head <NUM> and the probing machine <NUM> continue approaching to each other until the test surface 12a of the base body <NUM> touches, or adjacent to, the upper surface 22a of the test fixture <NUM>, and adjacent to the upper surface 26a of the load board <NUM>. In order to allow the probe sets protruding from the opening <NUM> to contact the pad <NUM> firmly, the test head <NUM> can first activate the vacuum function which means to exhaust air from a position on the base body <NUM> adjacent to the openings <NUM> when the test surface 12a of the base body <NUM> moves toward the upper surface 26a of the load board <NUM>. In other words, when the test surface 12a is pushed to the upper surface 26a, the sealing strip <NUM> will be pressed against the edge of the vacuum area <NUM>, so that the space enclosed by the test surface 12a, the upper surface 26a, and the sealing strip <NUM> is airtight. And then, the base body <NUM> can exhaust air from the test surface 12a. It is worth mentioning that when the test head <NUM> and the probing machine <NUM> are approaching to each other, the test head <NUM> and the probing machine <NUM> can perform the alignment procedures, such as aligning the alignment member <NUM> and the alignment member <NUM> with each other, and let the engaging member <NUM> fit or enter the engaging member <NUM>. The test head <NUM> and the probing machine <NUM> can be aligned first, or the test head <NUM> can start the vacuum function first, and these two steps should be interchangeable. In addition, in order to avoid excessive compression of the sealing strip <NUM> on the upper surface 26a and damage to the probe sets and the pads <NUM> protruding from the openings <NUM>, the metal strip <NUM> can be used as a support to maintain the gap between the test surface 12a and the upper surface 26a.

After the engaging member <NUM> enters the engaging member <NUM>, as described above, the user can pull the fixing element <NUM> on the test head <NUM> to lock the relative position of the engaging member <NUM> and the engaging member <NUM>. In this step, it can be said that the test head <NUM> has been fully connected or fixed to the probing machine <NUM>. It is worth mentioning that when the test head <NUM> has been connected to the probing machine <NUM>, part of the base body <NUM> will be pushed into the recess, the basin-shaped structure, of the test fixture <NUM>. For example, the recess, the basin-shaped structure, of the test fixture <NUM> may be square in appearance and have a width W3 in an axial direction. At this time, as long as the width W2 of the base body <NUM> in the axial direction is smaller than the width W3, part of the base body <NUM> can be sunk into the upper surface 24a, so that the test surface 12a of the base body <NUM> will be in the position between the upper surface 22a (or upper surface 26a) and the upper surface 24a. Different from the traditional pogo tower, if the traditional pogo tower is removed, the distance between the load board and the wafer will be too large, and there will be a problem that the load board cannot touch the wafer. In this embodiment, the test fixture <NUM> is designed to have a recess, the basin-shaped structure, so that the base body <NUM> can be pushed into the probing machine <NUM> and is closer to the load board <NUM>, thereby solving the problem that the load board cannot touch the wafer.

On the other hand, the vacuum function of the test head <NUM> mentioned in this embodiment can be used for other purposes in addition to stabilizing the electrical connection between the probe sets and the pads <NUM>. The test head <NUM> may be originally designed with the vacuum function, but it is not used to stabilize the electrical connection between the probe sets and the pads <NUM>. For example, the vacuum function may be designed to suck exhaust gas around the object under test or suck the replaced pogo tower, that is, a new application of the vacuum function is introduced in this embodiment.

In order to explain the test head connection method provided by the present invention, please refer to <FIG> together. <FIG> shows a flowchart of the test head connection method according to an embodiment of the present invention. As shown in the figures, in step S30, the load board <NUM> and the test fixture <NUM> are arranged between the test head <NUM> and the probing machine <NUM>. The test fixture <NUM> is set in the probing machine <NUM>, and the test fixture <NUM> is used for accommodating the load board <NUM>. In step S32, the vacuum function of the test head <NUM> is activated, and in step S34, the test head <NUM> is moved to align the test fixture <NUM>. Next, in step S36, the test head <NUM> is moved to contact the load board <NUM> in the test fixture <NUM>. And in step S38, the engaging member <NUM> and the engaging member <NUM> are used to fix the test head <NUM> and the test fixture <NUM>. In the above steps, the test head <NUM> and the probing machine <NUM> are connected in the direct probing connection, and the load board <NUM> can directly contact the wafer. The other steps of the test head connection method have been described in the previous embodiment, and this embodiment will not be repeated here.

Claim 1:
A test head connection method for connecting a test head (<NUM>) and a probing machine (<NUM>), comprising:
disposing a load board (<NUM>) and a test fixture (<NUM>) between the test head and the probing machine;
activating a vacuum function of the test head (<NUM>);
moving the test head (<NUM>) to align the test fixture;
moving the test head (<NUM>) until touching the load board (<NUM>) in the test fixture (<NUM>); and
fixing the test head (<NUM>) and the test fixture (<NUM>) by at least one engaging member (<NUM>, <NUM>);
wherein the test fixture (<NUM>) is disposed in the probing machine (<NUM>), and the test fixture (<NUM>) is used to accommodate the load board (<NUM>);
wherein the load board (<NUM>) is configured to connect a wafer by direct probing.