Electronic chip designed to be glued on

Abstract

Electronic chip intended to be glued. This description relates to an electronic chip (1000) comprising a first main face (100), intended to be glued, a second main face (200), lateral faces (301, 302, 303, 304), the second main face (200) comprising a central zone (210) and a peripheral zone (220) locally structured so as to form successively, from the central zone (210), a first part (221) having a first thickness, a second part (222) having a second thickness, the first thickness being less than the thickness of the central zone (210), the second thickness being greater than the first thickness and less than the thickness of the central zone (210). Figure for the abbreviation: Fig. 1

Description

Title of the invention: Electronic chip intended to be glued technical field

[0001] This description relates generally to the field of electronic chips, and more particularly to electronic chips that are to be glued onto a support. Previous technique

[0002] Electronic chips are sometimes mounted on substrates using a layer of adhesive. However, it frequently happens that the adhesive bleeds up the sides of the chip or even covers part of the front surface of the chip, which can reduce its performance, contaminate the front-facing connection pads, and / or contaminate the tools used to handle it ('pick and place tool'). To avoid these problems, the adhesive should not cover more than 80% of the chip's thickness.

[0003] However, managing the adhesive during chip attachment is difficult to control due to various factors: the nature of the adhesive, the type of chip and the cutting method used, the chip thickness, and the substrate design. Summary of the invention

[0004] There is a need to improve at least in part certain aspects of known processes for bonding electronic chips onto external elements, such as substrates.

[0005] This goal is achieved by an electronic chip comprising a first main face, intended to be glued onto a substrate, a second main face, lateral faces, the second main face comprising a central zone and a peripheral zone, the peripheral zone being locally structured at the level of a first edge, so as to form successively, from the central zone, a first part having a first thickness, a second part having a second thickness, the first thickness being less than the thickness of the central zone, the second thickness being greater than the first thickness and less than the thickness of the central zone.

[0006] According to a particular embodiment, the chip further comprises a third part having a third thickness, the third thickness being less than the second thickness, the second part being positioned between the first part and the third part.

[0007] According to a particular embodiment, the first layer is less than the third layer.

[0008] According to a particular embodiment, the peripheral zone is structured at the level of a second edge, the structuring at the level of the first edge and the structuring at the level of the second edge being able to be identical or different, the second edge preferably being opposite to the first edge.

[0009] According to a particular embodiment, the peripheral area is structured at the level of the four edges of the chip, the structuring of the four edges being, preferably, identical.

[0010] According to a particular embodiment, the second thickness represents 40 to 90% of the thickness of the central zone, preferably 50 to 80% of the thickness of the central zone.

[0011] According to a particular embodiment, the central zone has a thickness between 50 and 250 pm, preferably between 50 and 150 pm, even more preferably between 50 and 80 pm.

[0012] According to a particular embodiment, the difference in thickness between the first part and the second part is at least 2 pm and / or in which the width of the first part is at least 5 pm in order to be able to contain the solvent before its evaporation.

[0013] This goal is also achieved by an assembly method comprising a step in which a chip as defined above is assembled to an external element by means of a layer of glue, disposed between the chip and the external element.

[0014] This goal is also achieved by an assembly comprising a chip as defined above and an external element, such as a substrate, a layer of glue being disposed between the chip and the external element. Brief description of the drawings

[0015] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0016] Fig. 1 represents schematically, in side view and in section, a part of an electronic chip according to a particular embodiment;

[0017] [Fig.2] schematically represents, in three dimensions, an electronic chip according to another particular embodiment;

[0018] [Fig.3] schematically represents, in side view and in section, part of an electronic chip according to another particular embodiment;

[0019] [Fig.4] schematically represents, in side view and in section, part of an electronic chip according to another particular embodiment;

[0020] [Fig.5] schematically represents, in side view and in section, part of an assembly comprising an electronic chip and a substrate, assembled by means of a layer of glue, according to another particular embodiment;

[0021] [Fig.6] is an image obtained under an optical microscope of part of an assembly comprising an electronic chip and a substrate, assembled by means of a layer of glue, according to another particular embodiment;

[0022] [Fig.7] is an optical microscope image of part of an assembly comprising an electronic chip and a substrate, assembled using a layer of glue, according to a comparative example.

[0023] The different elements are not necessarily represented at a uniform scale in order to make the figures more legible. Description of the implementation methods

[0024] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0025] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0026] Also for the sake of clarity, the electronic components formed in or on the substrate are not shown.

[0027] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0028] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0029] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0030] Unless otherwise specified, between X and Y means that the terminals X and Y are included in the range.

[0031] Electronic components find applications in many industrial fields, and in particular, in the field of microelectromechanical systems (or MEMS (for 'micro electro mechanical system'), power amplifiers, proximity sensors or optical modules.

[0032] We will describe the electronic chip 1000 in more detail with reference to figures 1 to 5.

[0033] The chip 1000 comprises a first main face 100 and a second main face 200.

[0034] The first main face 100 is the rear face. This is the face intended to be glued to an external element.

[0035] The second main face 200 is the front face. This is the active face. The chip 1000 can comprise one or more discrete components. The discrete component(s) are, for example, chosen from transistors, diodes, thyristors, triacs, filters, etc. The chip can comprise one or more integrated electronic circuits. The chip allows the implementation of different electronic functions and can have various applications. By way of illustration, the chip can be a MEMS, a power amplifier, an optical sensor, or a microcontroller. The second face 200 also includes electrical connection pads (not shown).

[0036] The main faces 100, 200 are, for example, rectangular.

[0037] The chip 1000 further comprises side walls, generally four side walls 301, 302, 303, 304 resulting from the cutting of a semiconductor wafer. The side walls connect the first main face 100 to the second main face 200.

[0038] The second main face 200 comprises a central zone 210 and a peripheral zone 220. The peripheral zone 220 surrounds the central zone 210.

[0039] The active area of ​​the chip 1000 and the connection pads are located in the central area 210.

[0040] The central area 210 has a thickness corresponding to the thickness of the chip substrate.

[0041] The peripheral zone 220 is positioned on the edges of the second main face 200. In the case of a main face of rectangular shape, the peripheral zone is located on the four edges of the main face.

[0042] The peripheral zone 220 does not contain any components: it is a sacrificial zone.

[0043] The peripheral area is locally structured. Its structuring does not prevent the operation of the chip.

[0044] The structuring allows the creation of multiple interfaces on one or more edges of the chips 1000. When the chip 1000 is bonded to an external element 300 by its rear face 100, these interfaces will slow down or even stop the glue and prevent the glue from completely covering the side walls of the chip 1000.

[0045] At least one edge of the peripheral zone 220 is structured. Preferably, two edges of the peripheral zone are structured, with the edges being opposite each other. All edges of the peripheral zone can be structured. In other words, the structuring is carried out around the entire perimeter of the second face 200.

[0046] According to an alternative embodiment, for example shown in Figures 1 to 3 and 5, the structuring of the edge(s) of the peripheral zone 220 may include from the central zone 210 towards the edge of the chip 1000: - a first part 221 having a first thickness, - a second part 222 having a second thickness, - a third part 223 having a third thickness.

[0047] According to another embodiment, for example shown in [Fig.4], the structuring of the edge(s) of the peripheral area comprises, from the central area 210 to the edge of the chip 1000: - a first part 221 having a first thickness, - a second part 222 having a second thickness.

[0048] By thickness, we mean the dimension along the z-axis.

[0049] The width is defined along the y-axis.

[0050] According to these embodiment variants, either the second part 222 or the third part 223 forms a shoulder at the level of one of the lateral faces 301, 302, 303, 304. The shoulder allows to slow down the progression of the glue 400.

[0051] The second part 222 stops the progression of the glue 400. The second part has a width, for example, of more than 2 µm. The second thickness represents, for example, at least 40% of the thickness of the central zone 210, or even at least 50% of the thickness of the central zone 210. The second thickness represents, for example, at most 90% of the thickness of the central zone 210, or even at most 80% of the thickness of the central zone 210.

[0052] The first portion 221 has a thickness less than the thickness of the central zone 210 and the thickness of the second portion 222. The first portion 221 is formed between the central zone 210 and the second portion 222. The first portion 221 forms a groove in the peripheral zone 220. When assembled with an external element 300, for example a substrate, using a layer of adhesive 400, this groove will contain the adhesive solvent. It also prevents the adhesive from progressing towards the central zone 210, since the thickness of the first portion 221 is less than the thickness of the central zone 210.

[0053] The difference in thickness between the first part 221 and the second part 222 is, for example, at least 2 µm. The width of the first part is, for example, of at least 5 pm. The cavity formed allows the glue solvent to be contained before it evaporates.

[0054] With such chips, the 400 adhesive does not cover more than 80% of the chip thickness. For example, it covers between 20 and 80% of the thickness of the 1000 chip.

[0055] By way of illustration and not limitation, the structure of a chip as shown in [Fig. 1] and having a thickness greater than 50 pm, for example 70 pm or 80 pm, may have the characteristics given in the following Table 1:

[0056] [Tables 1] Thickness (pm) Width (pm) abcdef >50 >20 >5 >1 >2 >5

[0057] By way of illustration and not limitation, the structure of a chip as shown in [Fig.4] and having a thickness greater than 50 pm, for example 70 pm or 80 pm, may have the characteristics given in the following table 2:

[0058] [Tables2] Thickness (pm) Width (pm) a' c e' f >20 >5 >2 >5

[0059] One or more edges of parts 221, 222, 223 of the peripheral zone 220 may be beveled, as shown for example in [Fig.5]. In other words, they may have a bevel or chamfer.

[0060] Such 1000 chips can be formed by a process implementing one or more laser cutting and / or mechanical cutting and / or plasma engraving steps.

[0061] The chip 1000 can be assembled on an external element 300 by means of a layer of glue 400. The layer of glue 400 is disposed between the first face 100 of the chip and the external element 300.

[0062] Thanks to the structuring of the periphery 220 of the chip, the progression of the glue 400 is stopped at the level of the second part 222. The layer of glue 400 does not rise to more than 80% of the thickness of the chip (i.e. of the thickness of the central area), even for thin chips (typically less than 100 pm thick).

[0063] With such a chip, it is possible not only to use many pieces of equipment, including less expensive equipment, but also to have a wider choice of glue.

[0064] The number of control steps for the assemblies obtained is thus reduced. The yield is increased.

[0065] Adhesives that can be used in the assembly process are, for example, epoxy or silicone-type adhesives. The adhesives may contain particles, for example, insulating or conductive particles. The insulating particles may be alumina or silica particles. The conductive particles may be silver and / or copper particles.

[0066] 70 µm chips were structured as described above and glued onto a substrate. The glue extends up the side walls of the chip but covers less than 80% of the side wall thickness ([Fig. 6]).

[0067] If the chip is not structured, the glue can rise up to completely cover the side walls of the chip, even for chips of great thickness, typically more than 200 pm thick, for example 230 pm ([Fig.7]).

[0068] Such 1000 chips find applications in many industrial fields, and in particular, in the automotive field, for personal electronics, especially in the field of communication equipment, computers and peripherals. They can also be used in new GaN technologies, in power packages, and in electronic amplifiers.

[0069] This could, for example, refer to 5G connection devices or, more generally, connected devices.

[0070] It may also be an advanced driver-assistance system (ADAS for 'advanced driver-assistance Systems').

[0071] The 1000 electronic chip can be used in a smartphone or for the Internet of Things (IoT). The device is, for example, connected via 5G, Wi-Fi or Ultra-Wide Band (UWB).

[0072] The 1000 electronic chip may also be of interest for other fields, such as for the industrial field, in particular for green energies.

[0073] Such applications are given by way of illustration and are not limiting.

[0074] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0075] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Electronic chip (1000) comprising a first main face (100), intended to be glued onto a substrate, a second main face (200), side faces (301, 302, 303, 304), the second main face (200) comprising a central zone (210) and a peripheral zone (220), the peripheral zone (220) being locally structured at a first edge, so as to form successively, from the central zone (210), a first part (221) having a first thickness, a second part (222) having a second thickness, the first thickness being less than the thickness of the central zone (210), the second thickness being greater than the first thickness and less than the thickness of the central zone (210).

2. Chip according to the preceding claim, further comprising a third part (223) having a third thickness, the third thickness being less than the second thickness, the second part (222) being positioned between the first part (221) and the third part (223).

3. Chip according to any one of claims 1 and 2, wherein the first thickness is less than the third thickness.

4. Chip according to any one of the preceding claims, wherein the peripheral area (210) is structured at a second edge, the structuring at the first edge and the structuring at the second edge being able to be identical or different, the second edge preferably being opposite to the first edge.

5. Chip according to any one of claims 1 to 3, wherein the peripheral area (210) is structured at the four edges of the chip, the structuring of the four edges being, preferably, identical.

6. Chip according to any one of the preceding claims, wherein the second thickness represents from 40 to 90% of the thickness of the central zone (210), preferably from 50 to 80% of the thickness of the central zone (210).

7. Chip according to any one of claims 1 to 5, wherein the central zone (210) has a thickness of between 50 and 250 pm, preferably between 50 and 150 pm, even more preferably between 50 and 80 pm.

8. Chip according to any one of the preceding claims, wherein the difference in thickness between the first part (221) and the second part (222) is at least 2 pm and / or wherein the width of the first part (221) is at least 5 pm to be able to contain the solvent before its evaporation.

9. Assembly method comprising a step in which a chip (1000) as defined in any one of claims 1 to 8 is assembled to an external element (300) by means of a layer of glue (400), disposed between the chip (1000) and the external element (300).

10. Assembly comprising a chip (1000) as defined in any one of claims 1 to 8 and an external element (300), such as a substrate, a layer of glue (400) being disposed between the chip (1000) and the external element (300).

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