Sawing device for forming kerfs in semiconductor products and method therefor

Abstract

The present invention relates to a sawing device for forming kerfs in semiconductor products, the sawing device comprising: a carrier with a holding surface for holding the semiconductor product; a saw blade with a cutting edge movable relative to the carrier; a first position sensor for determining the position of a point on a free surface of the semiconductor product held by the carrier relative to the first position sensor; a second position sensor for determining the position of a point on the cutting edge of the saw blade relative to the second position sensor; and a control unit linked to the first and second position sensors, the control unit being configured to control the relative movement of the saw blade and the carrier.

Description

[Technical Field]

[0001] The present invention relates to a sawing device for forming kerfs in semiconductor products. The present invention also relates to a method for forming kerfs in semiconductor products. [Background technology]

[0002] In the final stage of semiconductor product manufacturing, manufactured integrated circuits (ICs) are singulated (diced) to obtain individual IC packages or dies. This singulation is sometimes performed by machining the substrate that interconnects the individual dies with a rotary saw blade. The substrate is typically a wafer, lead frame, or board. As part of the machining operation, the packaging material (often an epoxy resin) that encapsulates the dies is also typically separated at the same time. To minimize the shear forces exerted on the semiconductor product during the sawing operation, it is beneficial to maximize the sawing depth, thereby allowing the saw blade to exceed the thickness of the IC package as long as there is enough space for it to move behind the semiconductor product. The dimensions of this space are typically determined by the fixture or carrier that holds the semiconductor product during the singulation process. Therefore, it is important to be able to control the sawing depth very precisely to maximize the sawing depth on the one hand and to prevent the saw blade from digging into other parts of the fixture or sawing equipment on the other hand.

[0003] Alternatively, the displacement of the saw blade relative to the IC package may be limited by the thickness of the lead frame and, if present, the thickness of the packaging material. Limiting the saw depth in this manner is beneficial when singulation of individual IC packages is desired, but the underlying substrate, such as a foil material layer, must remain intact to maintain the layout of the separated IC packages for further processing. In this case, the IC packages ultimately remain connected through the foil material layer. As can be appreciated, in this case, close control of the sawing depth is important to completely separate the connected IC packages while avoiding cutting into the foil material layer.

[0004] In yet another scenario, saw machining of the substrate may be limited to a partial sawing operation, where the sawing depth is initially less than the thickness of the carrier, resulting in the formation of grooves in the carrier. In this case, separation of individual IC packages does not occur (or at least not initially). This latter sawing operation is applied to the manufacture of high-reliability IC packages (particularly quad-flat no-lead packages) that require solder-wettable flanks to form robust solder joints where the solder fillets adhere to the outer edges of the IC package. After the partial sawing operation, the resulting grooves are plated with a solderable surface finish. In a subsequent sawing operation, the IC package is singulated along the singulation lines adjacent to the grooves, creating solder-wettable step features at the singulation edges. This ensures proper solder wetting and therefore the formation of reliable solder joints when the IC package is later soldered to a printed circuit board. Furthermore, this enables automated optical inspection (AOI) of the solder joints. In order to form grooves with a specific depth with high precision, accurate control of the sawing depth is very important.

[0005] Even before singulation, IC packages are generally relatively small, typically on the order of a few millimeters. Moving parts of the singulation device, such as the carrier and saw blade, must be connected to the rest of the device by robust connections. Flexibility in these connections adversely affects the precision and accuracy required to create the saw grooves. As a result, the connections typically include relatively large and thick steel components to provide the stability necessary to make precise and accurate saw cuts. These connections or mechanical parts must fit into a relatively small section of the singulation device, near the carrier, to allow for interaction between the saw and carrier and to prevent the connections from becoming too long, unstable, or flexible.

[0006] WO 2021 / 167450 discloses a sawing apparatus for forming a kerf in a semiconductor product, the sawing apparatus comprising a carrier, a saw blade, a first position sensor, a second position sensor, a reference, and a control unit for controlling the relative movement of the saw blade and the carrier. To enable accurate kerfs using this sawing apparatus, measuring the distance from the first position sensor to the semiconductor product requires measuring at least three distances: the distance from the first position sensor to the surface of the reference, the distance from the second position sensor to the tip of the saw blade, and the distance from the second position sensor to another surface of the reference. The sawing apparatus disclosed in WO 2021 / 167450 requires a minimum of four measurements before creating a kerf.

[0007] Because IC packages are mass-produced products, the throughput speed of the singulation equipment is important to meet economic constraints. In other words, there is a limited amount of time available to cut the substrate into dies. Each measurement taken before sawing requires valuable time that cannot be spent on sawing. Furthermore, each additional measurement likely requires additional moving parts or additional sensors, further complicating the sawing equipment and increasing the probability of sawing equipment malfunction due to increased complexity. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the reliability and processing speed of forming kerfs with high accuracy and precision in semiconductor products. [Means for solving the problem]

[0009] The present invention provides a sawing device for forming kerfs in semiconductor products according to claim 1. Within the scope of the present invention, the free surface of the semiconductor product is the surface of the semiconductor product along which at least one controlled cut is made during the relative movement of the saw blade and the carrier. The cut can completely separate the semiconductor product into several IC packages, but can also form (shallow) grooves in the free surface that extend along only part of the height of the semiconductor product measured in a direction perpendicular to the free surface. Alternatively, the cut can separate the semiconductor products but leave the underlying foil material layer intact.

[0010] The sawing device of the present invention uses two position sensors: one for determining the position of the free surface of the semiconductor product and one for determining the position of the saw blade, particularly its cutting edge. By actually measuring the positions of the free surface of the semiconductor product (or at least a point thereon) and the cutting edge of the saw blade (or at least a point thereon), the amount of inference required to determine their relative positions is minimized, thus minimizing position errors when moving the carrier carrying the semiconductor product relative to the saw blade. For example, these measurements can be used to correct for unevenness in the cutting edge due to wear on the saw blade or differences in the height of the free surface due to warpage of the semiconductor product. This allows the sawing device to produce kerfs of a predetermined depth with high precision. Kerf depth is defined herein as the direction perpendicular to the free surface of the semiconductor product.

[0011] The use of two position sensors facilitates observing the free surface of the semiconductor product and the cutting edge of the saw blade at the point where the cutting edge contacts the free surface of the semiconductor product. Because the free surface of the semiconductor product faces the cutting edge of the saw blade, using a single position sensor that relies on a clear line of sight to the object being measured presents practical difficulties. Because circular saws are typically used, the cutting edge of the saw blade could theoretically be inspected on the side of the saw blade facing away from the free surface of the semiconductor product. However, inspecting the saw blade directly at the actual contact point eliminates position errors, for example, associated with the suspension of the saw blade.

[0012] A position sensor measures the position of an object relative to itself. However, to accurately control the relative movement of the saw blade and the carrier (and thus the semiconductor product connected to it) required to produce a precise kerf, the positions of the saw blade's cutting edge and the free surface of the semiconductor product must be determined relative to each other, not relative to the position sensor. This eliminates position sensor position errors. At the same time, the number of moving parts and the number of measurements must be limited to achieve the desired robustness of the device and a fast processing speed. Therefore, the present invention proposes the use of a fiducial that can link the position of a first position sensor to the position of a second position sensor. This fiducial takes the form of a physical object whose position can be obtained relative to the first position sensor through observation by the first position sensor, or whose position can be obtained relative to the second position sensor through observation by the second position sensor. The fiducial has a position relative to the first position sensor fixed via a holder, or a position relative to the second position sensor fixed via a holder. Within the scope of the present invention, a reference being fixed to the first or second position sensor via a holder means that during operation the positions of the reference, the first or second position sensor and the holder remain unchanged relative to each other.

[0013] The control unit is configured to convert the dimensions and position of the fiducial relative to the position sensor observable by the fiducial into the relative positions of the first and second position sensors. Using the position of the saw blade edge determined by the second position sensor in conjunction with the position of the free surface of the semiconductor product determined by the first position sensor, the control unit can determine the position of a point on the free surface of the semiconductor product relative to a point on the saw blade edge. Because the fiducial is fixed to either the first or second position sensor, it is not necessary to measure the distance between the fiducial and its corresponding fixed position sensor. This reduces the number of measurements required to create accurate and precise kerfs in the substrate. Furthermore, the number of moving parts in the device is reduced. As a result, both the processing speed and robustness of the sawing device are improved.

[0014] In particular, in a configuration in which the saw blade and the first position sensor are fixed relative to each other and the second position sensor and the reference are fixed relative to each other, only three measurements are required before a kerf can be made with high precision: a first measurement by the first position sensor measuring the position of the reference, a second measurement by the second position sensor measuring the distance to the tip of the saw blade, and a third measurement by the first position sensor measuring the distance to the surface of the semiconductor product. If the distance from the center of the saw blade to the first position sensor is approximately equal to the distance from the second position sensor to the reference, the first and second measurements can be performed simultaneously, improving the processing speed of the sawing device.

[0015] In another configuration in which the saw blade, the first position sensor, and the fiducial are all fixed relative to one another, only three measurements are required to make the kerf: a first measurement by the second position sensor measuring the distance to the tip of the saw blade, a second measurement by the second position sensor measuring the distance to the fiducial, and a third measurement by the first position sensor measuring the distance to the surface of the semiconductor product held by the carrier.

[0016] Advantageously, in either configuration, the sawing device only requires movement of the saw blade and the first position sensor, and optionally a reference attached thereto, for it to function. The extremely limited number of moving parts and the limited number of measurements required enable the sawing device to provide a cutting groove that is not only reliable and accurate, but also fast.

[0017] The position information obtained from both position sensors is then used to control the relative movement of the saw blade and the carrier with high precision. It should be noted that the position of the (free surface of) the semiconductor product, and therefore its moment relative to the saw blade, is also directly linked to the position of the carrier. That is, the carrier, also commonly called a jig or chuck, is configured to grip and hold the semiconductor product, for example by suction means, so that the position of the semiconductor product is fixed relative to the carrier. Controlling the relative movement of the saw blade and the carrier therefore means steering the saw blade relative to the semiconductor product, i.e., determining the position of the kerf, and in particular its depth.

[0018] The reference is formed by at least one reference surface on the holder observable by the first or second position sensor, which is configured to determine the position of a point on the reference surface. Thus, the reference surface, or at least the position of a point thereon, may be determined by the first or second position sensor. The first or second position sensor may independently determine the position of the reference surface relative to itself. Preferably, the distance spanned by the holder between the reference and the first or second position sensor is known and invariant.

[0019] Since the reference is formed by a reference surface fixed to the first position sensor or the second position sensor via a holder, it is preferable that the reference surface is not located between the saw blade and the second position sensor, since such an arrangement would prevent the second position sensor from measuring a point on the cutting edge of the saw blade.

[0020] Preferably, the first and second position sensors are not located between the saw blade and the carrier. The carrier is preferably movable only in a horizontal plane. Because the substrate to be cut is held in place by the carrier below it, unwanted movement of the carrier toward or away from the saw blade should be prevented. Meanwhile, the saw blade preferably moves only in a direction perpendicular to the horizontal plane in which the carrier can move while cutting the substrate. This mode of operation contributes to forming a very accurate cut groove in the substrate.

[0021] Due to the manner in which the carrier and the saw blade interact and the limited space between the saw blade and the carrier, it is advantageous for the first position sensor and / or the second position sensor not to be located between the saw blade and the carrier. Additionally, it would not be advantageous for the holder to connect both the first position sensor and the second position sensor so that the distance spanned between them is known and unchanging, since this would require a relatively large movable structure containing both position sensors to be located between the carrier and the saw blade, which would further increase the complexity of the sawing device.

[0022] The holder may be a first holder, and the first position sensor is fixed to a reference via the first holder, and the distance spanned by the first holder between the first position sensor and the reference is known and unchanging.

[0023] Additionally or alternatively, the distance spanned by the first holder between the first position sensor and the saw blade is known and invariant, in which case the position of the first position sensor relative to the saw blade (and vice versa) can also be determined because the dimensions of the first holder connecting the saw blade and the first position sensor are known.

[0024] The holder may also be a second holder, and the second position sensor is fixed to the reference via the second holder, and the distance spanned by the second holder between the second position sensor and the reference is known and unchanging.

[0025] The first position sensor and the carrier may be movable relative to each other. This may enable or simplify mapping of the free surface of the semiconductor product with a single position sensor. In this regard, the first position sensor may be configured to determine the positions of multiple points on the free surface of the semiconductor product. The control unit may be configured to process the positions of the multiple points on the free surface of the semiconductor product into a height profile of the free surface, and the control unit is configured to correct the height profile when controlling the relative movement of the saw blade and the carrier. This allows for the formation of kerfs with a constant depth, defined as the distance from the free surface in a direction perpendicular to the free surface, even if the free surface of the semiconductor product is not flat, for example due to warpage. Given the stringent requirements for dimensional consistency of the final IC package, it is important that any warpage in the semiconductor product can be corrected in the formation of the kerfs. This is particularly true for sawing device applications in which the semiconductor product undergoes only a partial sawing operation. A partial sawing operation is defined herein as an operation in which the sawing depth is smaller than the thickness of the semiconductor product, including the foil material layer. The partial sawing operation results in a semiconductor product with partial cuts or grooves in the surface of the semiconductor product. This may include the situation where the semiconductor product may be completely singulated into separate IC packages, but the underlying foil material layer remains intact and the orientation of the separated IC packages relative to each other is maintained. In the latter case, the sawing depth must be exactly the same as the local thickness of the semiconductor product excluding the foil material layer.

[0026] In one embodiment, the saw blade and the first position sensor are preferably not movable relative to each other, but are movable relative to the carrier and the second position sensor. Optionally, the carrier and the second position sensor are not movable relative to each other. This arrangement of the first position sensor, the second position sensor, the carrier, and the saw blade is advantageous because the number of moving parts is very limited. The moving parts may include the saw blade, the first position sensor, which is preferably fixedly connected to the saw blade, and either the second position sensor or the carrier. The second position sensor and the carrier may be movable relative to each other, but the second position sensor and / or the carrier may be fixedly positioned within the sawing device. In this way, the saw blade can cut the semiconductor product held by the carrier with high precision because the number of moving parts is relatively small.

[0027] The second position sensor and the saw blade may also be movable relative to each other. If the saw blade is rotatable, the second position sensor and the saw blade are already movable relative to each other, allowing the second position sensor to observe the entire cutting edge of the saw blade. This allows the second position sensor to have a fixed position relative to the sawing device. Alternatively, or together with the saw blade, the second position sensor may be movable relative to the sawing device. This latter case may be beneficial in reducing saw blade movement when determining the cutting edge position, potentially shortening the sawing operation and reducing wear and tear on the sawing device. The second position sensor is typically configured to determine the positions of multiple points on the cutting edge of the saw blade. This allows the position sensor, in cooperation with the control unit, to determine the height profile of the cutting edge, which changes due to wear of the saw blade. The second position sensor and the saw blade are preferably positioned relative to each other so that the cutting edge is directly observable by the position sensor at the position where the cutting edge contacts the free surface of the semiconductor product relative to the saw blade suspension. For example, if the free surface of the semiconductor is oriented downward, the second position sensor is configured to observe the position of the top along the cutting edge of the saw blade.

[0028] In a possible embodiment of the sawing device according to the present invention, at least one of the first and second position sensors is a distance sensor. The distance sensor is configured to measure the distance between itself and a given point that it is set to observe. This allows the distance sensor to determine the one-dimensional position of the point relative to itself. The relative movement of the saw blade and the carrier is then controlled in this dimension based on the position determined by the distance sensor. Thus, by determining the distance between the cutting edge of the saw blade and the free surface of the semiconductor product based on the respective measurements of the distance between the first position sensor and the free surface and the distance between the second position sensor and the cutting edge, it is possible to control the depth to which the saw blade penetrates the free surface. In a preferred embodiment, the distance sensor is a confocal sensor. Alternatively, the distance sensor may be formed by a triangulation sensor.

[0029] Information collected by a sawing device according to the present invention may be useful for quality control and / or gathering statistical information.

[0030] The present invention further relates to a method for forming kerfs in semiconductor products, as set forth in claim 11. In a processing step, knowledge of the relative positions of the first and second position sensors obtained through the reference is used to convert the positions of the free surface and the cutting edge (points) relative to each other from their respective sensor positions. This highly accurate position information allows for highly precise control of the relative movement of the saw blade and carrier, leading to accurate kerfs in the semiconductor product. The holder, and in particular the reference attached to it, is used to determine the position of either the first or second position sensor, which is not connected to the reference via the holder. Having one position sensor directly and fixedly connected to the reference substantially improves the accuracy and speed of kerf formation.

[0031] The first position sensor is capable of determining the positions of a plurality of points on the free surface of the semiconductor product, whereby the plurality of points on the free surface of the semiconductor product can be machined into a height profile of said free surface, which height profile is corrected in the movement of the saw blade relative to the carrier, which may have the effect of causing the cutting edge of the saw blade to follow the height profile of the free surface of the semiconductor product, resulting in a kerf of (more) uniform depth along the entire length of the kerf along the free surface of the semiconductor product, the kerf depth being again defined as the distance from the free surface in a direction perpendicular to said free surface.

[0032] The height profile of the free surface of the semiconductor product may be gradually followed by the cutting edge of the saw blade. This gradually following of the free surface of the semiconductor product can be achieved by adjusting the sawing depth, and therefore the distance the saw blade penetrates into the semiconductor product, a specific number of times over the length of the kerf. The smaller the adjustment interval, the better the saw blade can follow the height profile of the free surface semiconductor product, and the smaller the difference in kerf depth. Because the sawing depth is adjusted based on the relative position of the saw blade and the semiconductor product as determined by the position sensor, the number of adjustments typically does not exceed the measurement resolution, i.e., the number of points on the free surface of the semiconductor product whose positions are determined by the first position sensor.

[0033] Alternatively, the height profile of the free surface of the semiconductor product may be continuously followed by the cutting edge of the saw blade. For example, the saw blade may move along a straight line while forming (part of) the kerf. As a result, the kerf progresses slowly and is unable to follow local height differences in the free surface as well as it can follow the global height gradients that are typically found as a result of warpage in the semiconductor product. The path followed by the saw blade is generally determined by drawing a straight line between two points on the free surface of the semiconductor product and cutting into the free surface at a constant cutting depth relative to said line.

[0034] Alternatively, the trajectory followed by the saw blade may be determined by fitting a profile to distance measurements of multiple points on the free surface of the semiconductor product. In this case, the following of the free surface of the semiconductor product is obtained by adjusting the sawing depth, and therefore the distance the saw blade penetrates into the semiconductor product, based on the fitted profile. Thus, the height profile of the free surface of the semiconductor product is continuously followed by the cutting edge of the saw blade.

[0035] The position of a point on the cutting edge of the saw blade may be determined before the formation of successive kerfs. During each sawing operation, the saw blade wears. In order to take this wear into account in the formation of subsequent kerfs, it is necessary to measure the position of the cutting edge before the start of the next sawing operation. In practice, the positions of multiple points along the entire cutting edge of the saw blade are determined, thereby mapping the wear of the entire cutting edge so that it can be compensated for in the relative movement of the saw blade and carrier, and therefore in the formation of kerfs.

[0036] As a way to compensate for the wear of the saw blade edge even more accurately, the position of a point on the cutting edge can be determined before and after the formation of the kerf, and the difference in the position of said point on the cutting edge before and after the formation of the kerf can be used as feedforward information in controlling the relative movement of the saw blade and carrier in the formation of successive kerfs. In this case, the movement of the saw blade and carrier is compensated for the expected wear of the cutting edge by extrapolation. Therefore, the measured actual depth of the kerf can be used as an additional input for feedback steering of the subsequently sawed kerf.

[0037] The sawed semiconductor product may be subjected to control measurements in which the position of the kerf is recorded. Recording the position of the kerf may determine at least one of the kerf depth measured perpendicular to the free surface of the semiconductor product and the offset of the kerf measured in the plane of the free surface of the semiconductor product. The results of such post-processing measurements may form input for future sawing operations. This allows systematic errors in the position of the kerf, and therefore the position of points on the free surface of the semiconductor product relative to points on the cutting edge of the saw blade, to be detected and corrected.

[0038] The invention is further explained on the basis of non-limiting exemplary embodiments shown in the following drawings. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a schematic diagram of an embodiment of a sawing device according to the present invention; [Figure 2] 3 is a schematic view of another embodiment of a sawing device according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0040] The schematic diagram of FIG. 1 shows a sawing apparatus 1 including a carrier 2, also called a chuck or jig, and a saw blade 3. The carrier 2 includes a holding surface 4 for holding a semiconductor product 5. The holding surface 4 may be provided with, for example, suction or clamping means for holding the semiconductor product 5 stationary relative to the carrier 2. The semiconductor product 5 may be formed by several electrical components 6 (dies) mounted on a substrate 7, such as a wafer, lead frame, board, or any other form of substrate. The saw blade 3 in this example is rotary and can rotate about a suspension axis 8. The outer periphery of the saw blade 3 is formed by a cutting edge 9 that contacts and cuts into the semiconductor product 5 during the sawing operation. The carrier 2 and the saw blade 3 are movable relative to each other. In general, the sawing apparatus 1 is configured such that the second position sensor 15 is held stationary and the carrier 2 moves in at least one direction (direction x) to position the substrate 7. During operation, the saw blade 3 is movable in at least one direction z perpendicular to direction x. The interaction between the movement of the carrier 2 and the movement of the saw blade 3 allows the sawing of the substrate 7 .

[0041] The free surface 10 of the semiconductor product 5 facing away from the carrier 2 can be observed by a first position sensor 11 by moving the carrier over the first position sensor. In FIG. 1 , the first position sensor 11 observes a reference 12. In this particular example, the first position sensor 11 is formed by a distance sensor capable of determining the distance between itself and a point 13 on the free surface 10 of the semiconductor product 5, thereby determining the position of said point 13 on the free surface 10 essentially in one dimension. The cutting edge 9 of the saw blade 3, and in particular a point 14 on the cutting edge 9 that (in this case) faces upwards towards the free surface 10 of the semiconductor product 5, is observed by a second position sensor 15. Like the first position sensor 11, the second position sensor 15 is formed by a distance sensor capable of determining the distance between itself and a point 14 on the cutting edge 9 of the saw blade 3.

[0042] 1 and 2, the observation of the point 13, the reference plane 17 and the cutting edge 14 are indicated by dashed lines. If the dashed lines are not straight, the carrier 2 and / or the saw blade 3 must be moved relative to the second position sensor 15 before the observation can be made. The dashed lines are therefore examples of what can be observed by the position sensors 11, 15.

[0043] In FIG. 1 , the second position sensor 15 is connected to the reference 12 via the second holder 16. The distance between the second position sensor 15 and the reference 12 is known and unchanging. Therefore, the exact position of the reference 12 relative to the second position sensor 15 is determined by the shape and size of the second holder 16. The reference 12, particularly the reference surface 17 of the reference 12, can be detected by the first position sensor 11 by moving the reference 12 and the first position sensor 11 relative to each other. The second holder 16 can be shaped to fit within the limited space available within the sawing device 1. Both the reference 12 and the second position sensor 15 remain unchanging relative to each other during operation of the sawing device 1, but if any part of the reference 12, the second position sensor 15, or the second holder 16 itself fails, they can be replaced with a new reference 12 or second position sensor 15. Therefore, the second holder 16 can provide a storage space for locking both the reference 12 and the second position sensor 15 in their positions.

[0044] The position sensors 11, 15 and the drives 18, 19 responsible for moving the carrier 2 and the saw blade 3 relative to the second position sensor 15 are connected (via a data link connection 20) to a control unit 21. Data arising from the position sensors 11, 15 are transmitted to said control unit 21 via the connection 20 to said control unit 21, which processes said data into the position of the free surface 10 of the semiconductor product 5 relative to the cutting edge 9 of the saw blade 3.

[0045] 1 , a first holder 22 connects the saw blade 3 and the first position sensor 11. The distance between the saw blade 3 and the first position sensor is therefore known and fixed by the first holder 22. In operation, the control unit 21 is further configured to control the drives 18, 19 responsible for moving the carrier 2 and the saw blade 3 relative to each other, thereby controlling the relative movement of the saw blade 3 and the carrier 2 based on said information about the position of the free surface 10 of the semiconductor product 5 with respect to the cutting edge 9 of the saw blade 3. The control unit 21 may be formed by any type of suitable processing means and may comprise a plurality of modules which may be arranged at physically separated locations.

[0046] In FIG. 1 , a first holder 22 connecting the saw blade 3 and the first position sensor 11 fixes the relative positions of the saw blade 3 and the first position sensor 11. Similarly, a second holder 16 connecting the reference surface 12 and the second position sensor 15 fixes the relative positions of the second position sensor 15 and the reference surface 12. Because the positions of the reference 12 and the second position sensor 15 relative to each other are known, as are the positions of the saw blade 3 and the first position sensor 11 relative to each other, the number of measurements required per sawing operation is reduced. Furthermore, valuable space within the sawing apparatus 1 is used optimally, and the complexity of the sawing apparatus 1 is reduced.

[0047] The sawing device 1 has the advantage that the position of the cutting edge 14 of the saw blade 3 can be measured by the second position sensor 15, allowing the positioning of the carrier 2 relative to the saw blade 3 to be adjusted accordingly. If the size of the saw blade 3 decreases due to wear, the measurement value of the cutting edge 14 of the saw blade 3 will reflect this and the position of the carrier 2 relative to the cutting edge 14 can be adjusted appropriately. Furthermore, measurement of the surface 10 of the substrate 7 by the first position sensor 11 allows the position of the carrier 2 relative to the saw blade 3 to be adjusted in response to small curvatures or variations in height uniformity of the substrate 7.

[0048] FIG. 2 shows a schematic diagram of another sawing apparatus 1 according to the present invention. In this embodiment, the second holder 22 not only connects the saw blade 3 and the first position sensor 11 but also connects the reference 12. Unlike FIG. 1, in the embodiment of FIG. 2, the reference 12 is not connected to the second position sensor 15, and the second holder 16 is not present. Measuring the distance between the second position sensor 15 and the surface 17 of the reference 12 is preferably performed before determining the point 13 on the free surface 10 of the semiconductor product 5. Because the reference 12 in the embodiment shown in FIG. 2 is not connected to the second position sensor 15, the structure including the second position sensor 15 is less bulky, thereby saving space within the sawing apparatus. Furthermore, by connecting the saw blade 3, the first position sensor 11, and the reference 12 together via the first holder 22, the complexity of the sawing apparatus 1 is further reduced.

Claims

1. 1. A sawing device for forming a kerf in a semiconductor product, comprising: a carrier having a holding surface for holding the semiconductor product; a saw blade having a cutting edge, the saw blade being movable relative to the carrier; a first position sensor for determining a position of a point on a free surface of the semiconductor product held by the carrier relative to the first position sensor; a second position sensor for determining the position of a point on the cutting edge of the saw blade relative to the second position sensor; a control unit linked to the first position sensor and the second position sensor and configured to control the relative movement of the saw blade and the carrier; Equipped with the sawing device further comprises a reference for linking a position of the first position sensor to a position of the second position sensor, the reference being fixed to the first position sensor or the second position sensor via a holder; The control unit using the reference to process the position determined by the first position sensor and the second position sensor into a position of the point on the free surface of the semiconductor article relative to the point on the cutting edge of the saw blade; controlling the relative movement of the saw blade and the carrier based on the position of the point on the free surface of the semiconductor product relative to the point on the cutting edge of the saw blade. It is configured as follows: the reference is formed by a reference surface on the holder observable by the first position sensor or the second position sensor, the first position sensor or the second position sensor being configured to determine the position of a point on the reference surface; the distance spanned by the holder between the reference and the first position sensor or the second position sensor is known and invariant; Saw cutting equipment.

2. 2. The sawing device of claim 1, wherein the holder is a first holder, the first position sensor is fixed to the reference via the first holder, and the first holder spans a known and unchanging distance between the first position sensor and the reference.

3. 3. The sawing device of claim 2, wherein the distance spanned by the first holder between the first position sensor and the saw blade is known and invariable.

4. 2. The sawing device of claim 1, wherein the holder is a second holder, the second position sensor is fixed to the reference via the second holder, and the distance spanned by the second holder between the second position sensor and the reference is known and invariable.

5. 5. Sawing device according to any one of claims 1 to 4, characterized in that the first position sensor and the carrier are movable relative to each other.

6. 6. Sawing device according to any one of claims 1 to 5, characterized in that the second position sensor and the saw blade are movable relative to each other.

7. 7. The sawing device according to claim 1, wherein the saw blade and the first position sensor are not movable relative to each other, but the saw blade and the first position sensor are movable relative to the carrier and the second position sensor.

8. 8. Sawing device according to any one of the preceding claims, characterized in that the first position sensor is adapted to determine the positions of a plurality of points on the free surface of the semiconductor product.

9. 9. The sawing device according to claim 8, wherein the control unit is configured to process the positions of the points on the free surface of the semiconductor product into a height profile of the free surface, and the control unit is configured to compensate for the height profile in the control of the relative movement of the saw blade and the carrier.

10. 10. Sawing device according to any one of the preceding claims, characterized in that the second position sensor is configured to determine the position of a plurality of points on the cutting edge of the saw blade.

11. 11. Sawing device according to any one of the preceding claims, characterized in that at least one of the first and second position sensors is a distance sensor, in particular a confocal sensor.

12. holding the semiconductor product with a carrier; determining a position of a point on a free surface of the semiconductor article using a first position sensor; determining the position of a point on the cutting edge of the saw blade using a second position sensor; linking the position of the first position sensor to the position of the second position sensor using a reference; using the reference to process the position determined by the first position sensor and the second position sensor into a position of the point on the free surface of the semiconductor product relative to the point on the cutting edge of the saw blade; moving the saw blade relative to the carrier based on the position of the cutting edge of the saw blade relative to the bottom surface of the semiconductor product, thereby cutting into the free surface of the semiconductor product; Including, the reference for linking the position of the first position sensor to the position of the second position sensor is determined by a reference plane observed by the first position sensor or the second position sensor; a distance between the reference and the first position sensor is known and unchanging, or a distance between the reference and the second position sensor is known and unchanging; the first position sensor and / or the second position sensor determine the position of the point relative to the reference surface; A method for forming kerfs in a semiconductor product.

13. 13. The method of claim 12, wherein the positions of a plurality of points on the free surface of the semiconductor article are determined by the first position sensor.

14. 14. The method according to claim 12 or 13, characterized in that the points on the free surface of the semiconductor product are machined into a height profile of the free surface, and the height profile is corrected in the movement of the saw blade relative to the carrier.

15. 15. The method of claim 14, wherein the height profile of the free surface of the semiconductor article is continuously followed by the cutting edge of the saw blade.

16. 16. A method according to any one of claims 12 to 15, characterized in that the position of a point on the cutting edge of the saw blade is determined before and after the formation of kerfs, and the difference in the position of the point on the cutting edge before and after the formation of kerfs is used as feed forward information in controlling the relative movement of the saw blade and the carrier in the formation of successive kerfs.

17. 17. Method according to any one of claims 12 to 16, characterized in that the sawed semiconductor product is subjected to a control measurement in which the depth and position of the kerfs are recorded.

18. 18. The method of claim 17, wherein in recording the position of the kerf, at least one of a kerf depth measured perpendicular to the free surface of the semiconductor article and a kerf offset measured in the plane of the free surface of the semiconductor article is determined.

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