CN108695588A - Integrated circuit and antenna crystal grain and integrated method - Google Patents

Abstract

The invention discloses a crystal grain for integrating a circuit and an antenna and an integration method. The circuit and the antenna are respectively positioned on the front surface and the back surface which are opposite to the substrate, but are electrically coupled to the shared potential reference positioned on the substrate. In order to maintain the mechanical strength of the whole die, dummy metals separated from the antenna are distributed around the antenna on the back surface of the substrate where the antenna is located. In addition, to reduce the side effects caused by induced currents, a number of earth contacts are provided on one or more surfaces of the substrate.

Description

Die and Integration Method of Integrated Circuit and Antenna

technical field

The present invention relates to a crystal grain and an integration method of an integrated circuit and an antenna in which the circuit and the antenna are respectively formed on the front surface and the back surface of the substrate but share a common potential reference (shared ground). On the back surface of the substrate, dummy metals are used to electrically isolate the antenna from each other to maintain the overall mechanical strength (mechanical strength) of the chip and integration method of the integrated circuit and the antenna.

Background technique

With the development of the semiconductor industry over the years, the circuits used to process and store signals (whether active circuits or passive circuits, or memory) and the antennas used to receive and/or transmit electromagnetic signals are generally located in different integrated circuits. superior. Although the dies with circuits and the dies with antennas can be located on the same printed circuit board (PCB), or the dies with circuits are located on one side of a printed circuit board and the antenna (or Die with antenna) is on the other side of this PCB.

However, there has been a desire to integrate circuitry and antennas on the same die, as this reduces the number of dies used, reduces the printed circuit board area occupied, and reduces the need to transmit electromagnetic signals between different dies . However, so far, if the circuit and the antenna are to be integrated into the same chip, at least the following technical problems will be faced: 1) For most commercially used electromagnetic wave frequencies, the area of the antenna is significantly larger than the area of the circuit, The distribution of the two on the crystal grains is not easy to match and integrate. 2) There is mutual interference between the antenna and the circuit, especially when receiving and/or emitting electromagnetic waves at both ends of the antenna will cause strong interference to the surrounding circuits. 3) If both the circuit and the antenna are to be placed on the same surface of the die, it will not only occupy a large area but also interfere with each other. 4) If the circuit and the antenna are to be placed on the opposite surface of the crystal grain, how to transmit the signal between the antenna and the circuit, how to maintain the mechanical strength of the grain, and how to deal with the potential reference of the circuit and the antenna, etc. unresolved issues.

There is a need to provide a chip and an integration method for integrating a circuit and an antenna, especially when the frequency of electromagnetic waves for commercial applications has gradually progressed to the point where the size of the antenna is similar to the size of the circuit.

Contents of the invention

In the present invention, the antenna and the circuit are arranged on different surfaces of the substrate and the same shared potential reference is used, and some virtual metals separated from the antenna can be arranged on a certain surface of the substrate where the antenna is located to maintain the mechanical strength of the entire grain and conform to manufacturing process requirements. In addition, one or more ground balls can be used to connect between the die and the printed circuit board (or between the die and the outside of the die) to reduce the influence of the induced current, and the die There may be silicon vias in the substrate of the chip to electrically connect the circuit and the antenna.

The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. An integrated circuit and antenna chip according to the present invention includes: a substrate, the substrate has a front surface and a back surface; a circuit, located on the front surface; an antenna, located on the back surface; and a shared potential reference, electrically connected to the circuit and the antenna.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

The aforementioned crystal grain is characterized in that it further comprises at least one of the following: the shared potential reference is located on the front surface; the shared potential reference is located on the side surface of the substrate; the shared potential reference is located inside the substrate; and the shared potential reference Located inside the substrate and between the antenna and the circuit.

For the aforementioned die, the shared potential reference is the potential reference used by the circuit regardless of the presence of the antenna.

In the aforementioned die, the position of the antenna on the back surface can be elastically adjusted and does not have to be located in the middle of the back surface or overlap with the circuit in a direction perpendicular to the front surface and the back surface .

As mentioned above, the size of the antenna is proportional to the wavelength of the electromagnetic waves that the antenna is designed to receive and emit.

For the aforementioned die, the area ratio of the antenna to the back surface is as large as possible when the antenna is a resonant antenna, and there is no limit when the antenna is a non-resonant antenna.

The aforementioned die includes a plurality of dummy metals on the back surface surrounding the antenna but separated from the antenna.

For the aforementioned grain, the ratio of the area of the antenna and the dummy metal to the back surface and the distribution on the back surface depend on at least the following two points: the mechanical strength of the grain and the manufacturing process of the grain .

For the aforementioned crystal grain, the distribution restriction of the dummy metal on the back surface includes at least one of the following: the distance between the dummy metal and the antenna is relatively far near the two ends of the antenna receiving and/or emitting electromagnetic waves, and The distance between the dummy metal near other parts of the antenna and the antenna is relatively close; the distribution of the dummy metal near the two ends of the antenna receiving and/or emitting electromagnetic waves is relatively sparse, while the dummy metal near other parts of the antenna The distribution of the metals is relatively dense; and the areas of the dummy metals near the two ends of the antenna receiving and/or emitting electromagnetic waves are relatively small, while the areas of the dummy metals near other parts of the antenna are relatively large.

For the aforementioned crystal grain, the distribution limit of the dummy metal on the back surface includes at least one of the following: the distribution of the dummy metal in the part closer to the antenna is relatively sparse, and the part farther away from the antenna The distribution of the dummy metal is relatively dense; and the size of the part of the dummy metal nearer to the antenna is smaller, while the size of the part of the dummy metal farther away from the antenna is larger.

For the aforementioned crystal grain, the distribution limit of the virtual metal on the back surface includes at least one of the following: the distance between the virtual metal and the antenna is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit; the virtual metal The distance between the metal and the two ends in the longitudinal direction of the antenna is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit; the wavelength of electromagnetic waves.

For the aforementioned crystal grain, when the antenna is designed to receive and/or transmit electromagnetic waves with a frequency between 80 GHz and 650 GHz, the distribution limit of the dummy metal on the back surface at least includes one of the following: the dummy metal The gap between the metals is greater than 50 microns; the length of any side of any one of the virtual metals is greater than 150 microns; and the shape of any one of the virtual metals is quadrilateral or rectangular.

The aforesaid crystal grain includes a plurality of ground balls, and different ground balls are respectively connected to different parts of the virtual metal.

The aforementioned grains include at least one of the following: the ground balls are evenly distributed on the front surface; the ground balls are evenly distributed on the back surface; the ground balls are distributed on the front surface; The grounding balls are distributed on the negative surface; the grounding balls are distributed on one or more side surfaces of the substrate; and the grounding balls are distributed on the substrate when the antenna receives and/or emits electromagnetic waves, and the induction current is denser the stronger part.

For the aforementioned die, the ground balls are gold bumps or solder balls.

The purpose of the present invention and the solution to its technical problem also adopt the following technical solutions to achieve. According to a method of integrating a circuit and an antenna in the same chip proposed by the present invention, it includes: a. setting the circuit distribution on the front surface of the substrate, the antenna and a plurality of dummy metals on the back surface of the substrate, and a plurality of dummy metals on the substrate distribution of multiple grounding balls on one or more surfaces; b. simulate the antenna, the virtual metal and the electromagnetic field and current distribution on the grounding ball when the antenna receives and transmits electromagnetic waves; c. adjust the antenna according to the simulation results , the distribution of the virtual metal and the grounding ball; d. Repeat steps b and c until the electromagnetic field and current distribution on the antenna, the virtual metal and the grounding ball meet the requirements; here, the circuit The antenna is electrically connected to a shared potential reference; here, the dummy metal surrounds the antenna and is separated from the antenna; here, different ground balls are respectively connected to different surfaces of one or more surfaces of the substrate. part.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

The aforementioned method includes fixing the antenna in steps b and c and only repeatedly adjusting the dummy metal and the ground ball until they meet requirements.

The aforementioned method includes fixing the antenna and the grounding ball in steps b and c, and only repeatedly adjusting the virtual metal until it meets the requirements.

In the aforementioned method, step c includes adjusting at least one of the following: the size of at least one of the virtual metals, the shape of at least one of the virtual metals, the distance between at least two of the virtual metals, the distance between at least one of the virtual metals and the antenna distance, the position of the part of the virtual metal around the antenna, and the quantity and position of the virtual metal.

In the aforementioned method, step c includes at least one of the following: making the size of the virtual metals as small as possible, making the distance between the virtual metals as small as possible, making the part farther away from the antenna The size of the dummy metal is larger, the size of the dummy metal closer to the antenna is smaller, and the distance between the dummy metal and both ends of the antenna is as large as possible.

The foregoing method includes at least one of the following: placing the antenna in the middle of the back surface; placing the antenna around the back surface; allowing the antenna to be connected to the circuit in a direction perpendicular to the front surface and the back surface overlap each other; make the antenna separate from the circuit in a direction perpendicular to the front surface and the back surface; design the size of the antenna in proportion to the wavelength of the electromagnetic wave that the antenna is designed to receive and emit; and when When the antenna is a resonant antenna, the antenna occupies a larger proportion of the back surface.

The aforementioned method includes at least one of the following: using the potential reference used by the circuit regardless of whether the antenna exists or not as the shared potential reference; placing the shared potential reference inside the substrate and between the antenna and the circuit place the shared potential reference on the front surface; place the shared potential reference on the side surface of the substrate; and place the shared potential reference inside the substrate.

The aforementioned method includes setting the proportion of the area shared by the antenna and the dummy metal on the back surface and the common distribution on the back surface according to the mechanical strength of the crystal grain and the manufacturing process of the crystal grain.

The aforementioned method includes adjusting the distribution of the dummy metal on the back surface according to at least one of the following: the distance between the dummy metal and the antenna near the two ends of the antenna receiving and/or emitting electromagnetic waves is relatively long, The distance between the dummy metal near other parts of the antenna and the antenna is relatively close; the distribution of the dummy metal near the two ends of the antenna receiving and/or emitting electromagnetic waves is relatively sparse, and in other parts of the antenna The distribution of the dummy metals near the part is relatively dense; and the dummy metals near the two ends of the antenna receiving and/or emitting electromagnetic waves each have a small area, and the parts near the other parts of the antenna Each of the dummy metals has a relatively large area.

The foregoing method includes adjusting the distribution of the dummy metal on the back surface according to at least one of the following: the distribution of the dummy metal is relatively sparse in the part closer to the antenna, and the distribution of the dummy metal in the part farther away from the antenna is relatively sparse. The distribution of the dummy metal is relatively dense; and the size of the dummy metal is smaller in a part closer to the antenna, and larger in a part farther away from the antenna.

The aforementioned method includes adjusting the distribution of the dummy metal on the back surface according to at least one of the following: the gap between the dummy metals is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit; The distance between the virtual metal and the two ends in the longitudinal direction of the antenna is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit; and the gap between the virtual metals is proportional to the wavelength that the antenna is designed to receive and/or The wavelength of the emitted electromagnetic waves.

The foregoing method includes at least one of the following: allowing the ground ball to be evenly distributed on the front surface of the part where the antenna is located; allowing the ground ball to be evenly distributed on the back surface of the part where the virtual metal is located; distributing the ground ball on the front surface of the part where the antenna is located; distributing the ground ball on the back surface of the part where the dummy metal is located; and distributing the ground ball on the receiving and/or Or the part where the induced current is denser and stronger on the virtual metal when electromagnetic waves are emitted.

The aforementioned methods include using gold bumps or solder balls as the ground balls.

In the aforementioned method, when the antenna is designed to receive and/or transmit electromagnetic waves with a frequency between 80 GHz and 650 GHz, step b and step c further include at least one of the following: make the gap between the virtual metals greater than 50 microns; allowing any side length of any one of the virtual metals to be greater than 150 microns; and allowing any one of the virtual metals to be quadrangular or rectangular in shape.

Generally, the shared potential reference is located inside the substrate and between the front surface and the back surface of the substrate, but the invention does not limit the details of the shared potential reference. That is, there is no need to limit the details of changing the circuit and/or antenna because of the details of the shared potential reference, and it is not necessary to limit the change of how the circuit and/or antenna are placed on the front surface of the substrate and/or because of the shared potential reference. back surface.

Generally, the circuit is located on the front surface of the substrate and the antenna is located on the back surface of the antenna, and the present invention does not limit the details of the distribution of the antenna on the back surface. That is, the antenna can either be located at the center of the back surface of the substrate or at the periphery of the back surface of the substrate, that is, the antenna can overlap or be separated from the circuit on the front surface of the substrate in a direction perpendicular to the two surfaces.

Generally speaking, the distribution of dummy metals on the back surface of the substrate is limited to being separated from the antenna. The present invention can flexibly adjust the details of the distribution of dummy metals on the back surface of the substrate, regardless of the number, shape, area and spacing of dummy metals, etc. , or the relative relationship between the virtual metal and the antenna. The distribution of the virtual metal on the back surface of the substrate is not only related to the geometrical profile of the antenna and the frequency of the electromagnetic waves that the antenna is designed to receive and emit, but also related to the mechanical strength of the entire crystal grain and the requirements of the manufacturing/processing process.

Generally speaking, the use of the ground ball is to guide the induced current caused by the electromagnetic wave to be received and/or emitted by the antenna to the printed circuit board, and the ground ball may be evenly distributed around the antenna on the back surface of the substrate. , or can be uniformly distributed around the circuit on the front surface of the substrate, or can be distributed on one or more surfaces of the substrate, or can be concentrated at the position where the induced current intensity/number is obvious, the present invention does not The number and distribution details of the ground balls are not limited.

Generally speaking, the method of integrating the antenna and the circuit into the same chip is to first set the distribution of the antenna and dummy metal on the back surface of the substrate and the grounding ball on one or more surfaces of the substrate, and then conduct electromagnetic field and Analyze the current, and then adjust the distribution of the antenna, virtual metal and grounding ball according to the simulation results, and then conduct computer simulation again to analyze the electromagnetic field and current. This is repeated until a certain distribution of antennas, virtual metals and ground balls meets the requirements. Usually, the position and shape of the antenna on the back surface of the die are fixed, that is, the present invention often focuses on repeatedly adjusting the dummy metal and the ground ball until it meets the requirement. Moreover, because the connection between the ground ball and the printed circuit board needs to consider other factors and not only the condition on the back surface of the substrate, the present invention often repeatedly adjusts the dummy metal under a certain ground ball distribution until it meets the requirements.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1A and FIG. 1B are the basic structure and a sample structure of the chip of the integrated circuit and the antenna proposed by the present invention.

2A and 2B schematically depict two sample structures of integrated circuit and antenna dies using dummy metal.

2C-2E schematically show three possible variations of the integrated circuit and antenna die using dummy metal.

3A and 3B schematically show two sample structures of two integrated circuit and antenna dies using ground balls.

FIG. 4A and FIG. 4B show the basic flow of the integrated circuit and antenna chip integration method proposed by the present invention.

[Description of main component symbols]

11: Substrate 12: Circuit

13: Antenna 14: Shared potential reference

15: TSV 16: Virtual metal

17: Earth Ball 401: Step Box

402: Step Box 403: Step Box

404: judgment box

Detailed ways

A detailed description of the present invention will be discussed by means of the following examples, which are not intended to limit the scope of the present invention, but may be applicable in other applications. The illustrations reveal some details, it being understood that the details disclosed may differ from those disclosed, except in the case of expressly limited characteristics.

Since the side length of a general grain is often only a few millimeters (millimeter), otherwise the signal transmission and heat dissipation of the circuit (whether it is an active circuit or a passive circuit, or a memory) used to process and store signals in the grain, etc. The problem will make the overall performance not optimal, but the wavelength of the electromagnetic wave used in the past is often significantly longer than a few centimeters, especially the electromagnetic wave wavelength corresponding to the antenna that can be integrated on the chip is often significantly longer than a few centimeters. Therefore, if the circuit for processing and storing signals and the antenna for receiving and transmitting electromagnetic waves are to be integrated into the same chip, basically only the chip with the circuit and the chip with the antenna are packaged ( package) technology, not only does not save the amount of die usage and die area, but also has to deal with the mutual interference between the circuit and the antenna, signal transmission and other issues.

However, as electromagnetic waves such as Terahertz-Gigahertz waves (Terahertz-Gigahertz waves) and other frequencies ranging from tens of gigahertz (GHz) to several terahertz (THz) are gradually being practically applied to such as security inspection tools, communication and In the field of material analysis and so on, the size of the antenna used to receive and transmit electromagnetic waves can be approximately equal to or even smaller than the size of the circuit used to process and store electromagnetic waves. That is, it is possible to place the circuit and the antenna on opposite surfaces of the same chip, thereby saving the number of chips used and reducing the area of the chip, as long as the signal transmission and communication between the circuit and the antenna can be effectively handled. Issues such as mutual interference and the need to properly maintain the mechanical strength of the entire die.

In response to such a development trend, the present invention proposes a chip and an integration method of an integrated circuit and an antenna, and illustrates the present invention through the following embodiments and related discussions.

1A shows the basic structure of the integrated circuit and antenna chip proposed by the present invention, the circuit 12 is located on the front surface of the substrate 11 and the antenna 13 is located on the back surface of the substrate 11, and the circuit 12 and the antenna 13 are electrically connected to Shared potential reference 14. Obviously, by forming the circuit 12 and the antenna 13 on two opposite surfaces of the same substrate 13, not only the material and thickness of the substrate 11 can be used to reduce the mutual interference between the circuit 12 and the antenna 13, especially the antenna 13 Interaction with the coupler (coupler) in the circuit 12, and because the circuit 12 and the antenna 13 can overlap each other in the direction perpendicular to the front surface and the back surface, the area of the integrated antenna and the circuit can be reduced, Especially when the wavelengths of the electromagnetic waves to be received and emitted by the antenna 13 make the dimensions of the antenna 13 and the circuit 12 the same or differ by at most several times. In addition, since the potential reference of the circuit 12 and the antenna 13 is the same, the operation of the two has a common reference. The process of transmitting electromagnetic signals to the antenna 13 to emit electromagnetic waves can operate smoothly.

FIG. 1B shows an example structure of a die for an integrated circuit and antenna. The circuit 12 and the antenna 13 are located on two opposite surfaces of the substrate 11 , a TSV (Through Silicon Via, TSV) 15 is electrically connected to the circuit 12 and the antenna 13 , and the shared potential reference 14 is located inside the substrate 11 and separated from the TSV 15 .

It must be emphasized that the present invention is not limited to the details of the circuit 12 , the antenna 13 and the shared potential reference 14 . For example, in different embodiments, the shared potential reference 14 is either located inside the substrate 11 between the antenna 13 and the circuit 12, or located on the side surface of the substrate 11, or located on the front surface of the substrate 11 and separated from the circuit 12 or located on the back surface of the substrate 11 and separated from the antenna 13 . For example, if the present invention is viewed as integrating the antenna 13 into the substrate 11 that originally has the circuit 12 , the potential reference used by the circuit 12 regardless of whether the antenna 13 exists can be directly used as the shared potential reference 14 . For example, the circuit 12 may use a Complementary-Conducting-Strip Structure (CCS structure), and the shared potential reference 14 is the potential reference used by such a complementary conductive-strip structure.

The invention is also not limited to other details of the integrated circuit and antenna die. For example, the material of the substrate 11 can be silicon or gallium arsenide or other substrate materials that can be used in the semiconductor industry. For example, the substrate 11 may also include a surface located on the substrate 11 (whether it is a front surface, a back surface or a side surface) that is electrically isolated from the circuit 12 and the antenna 13 or is used to electrically isolate the shared potential reference from the circuit 12. As for the dielectric layer of both the antenna 13 and the antenna 13, any dielectric material that can be used in the semiconductor industry can be used for the dielectric layer.

In addition, the present invention only restricts the circuit 12 and the antenna 13 to be located on two opposite surfaces of the substrate 11 (or even just two different surfaces), and the relationship between the circuit 12 and the antenna 13 relative to the substrate 11 is not required. Many restrictions. For example, the position of the antenna 13 on the back surface can be elastically adjusted, or can be located in the middle of the back surface, or can be located around the back surface, or can be with the circuit 12 in a direction perpendicular to the front surface and the back surface overlap each other, or may be separated from the circuit 12 in a direction perpendicular to the front surface and the back surface. For example, the size of the antenna 13 is proportional to the wavelength of the electromagnetic waves that the antenna 13 is designed to receive and emit. For example, the area ratio of the antenna 13 to the back surface can be adjusted. When the antenna 13 is a resonant antenna (resonant antenna), the larger the better, and the antenna 13 is a non-resonant antenna (non-resonant antenna). This ratio is relatively unlimited.

In order to ensure that the antenna 13 can properly receive and transmit electromagnetic waves, there should preferably be no structures/materials around the antenna 13 that would affect the transmission of electromagnetic waves and/or interact with the antenna 13 . That is to say, some embodiments of the present invention allow only the antenna 13 to exist on the back surface of the substrate 11, and at most add some connections for connecting the substrate 11 with the circuit 12 and the antenna 13 to the printed circuit board. element.

However, limited by the mechanical strength requirements of the entire die or the requirements of the fab (or even the packaging plant) for the manufacturing process, if the back surface of the substrate 11 only has the antenna 13, or the die of the integrated circuit and the antenna of the final product The mechanical strength of the substrate is not strong enough to be easily damaged, or the substrate 11 or the antenna 13 may be damaged during the manufacturing process, so that the crystal grains of the integrated circuit and the antenna cannot be properly manufactured. Although increasing the ratio of the antenna 13 to the back surface of the substrate 11 may enhance the mechanical strength of the grain or meet the requirements of the fab (or even the packaging plant) for the manufacturing process, but due to the size of the antenna 13 and the antenna 13 to be received and/or or the emitted electromagnetic wave wavelength, if the area of the antenna 13 is excessively increased (such as the width of the antenna 13 ), it may also cause defects such as an increase in leakage current.

Therefore, in some embodiments of the present invention, a plurality of dummy metals are placed on the back surface of the substrate 11 to provide the required mechanical strength together with the antenna 13 or meet the requirements of the manufacturing process. Thereby, the size, shape, area, etc. of the antenna 13 can be optimized for the electromagnetic waves to be received and emitted, and the required mechanical strength and manufacturing process requirements can be achieved by adjusting the size, shape, distribution, etc. of the virtual metal. . Of course, in order to minimize possible negative effects on the antenna 13, these dummy metals are separated from the antenna 13. In addition, in order to achieve the required mechanical strength and manufacturing process requirements, these dummy metals often surround the antenna 13 unless the antenna 13 is located on the edge of the back surface of the substrate 11 so that the dummy metals can only be located on other parts of the back surface of the substrate 11 . In addition, any dummy metal and the shared potential reference 14 may or may not be electrically isolated from each other, that is, there is no need to limit whether any dummy metal and the shared potential reference 14 are electrically isolated from each other. Here, FIGS. 2A and 2B briefly describe two sample structures of integrated circuit and antenna dies using dummy metal 16 .

Obviously, since the use of the dummy metal 16 comes from the requirements for the mechanical strength of the grain and/or the requirements for the manufacturing process of the grain, the area ratio of the antenna 13 and the dummy metal 16 occupying the back surface is the same as that on the back surface. The distribution mode of the crystal grains depends at least on the mechanical strength of the crystal grains and the grain production process. That is to say, the present invention can flexibly adjust the area ratio of the antenna 13 and the dummy metal 16 on the back surface of the substrate 11 depending on the actual specifications of the die or the manufacturing process parameters and manufacturing process specifications of the fab, etc. and distribution.

In any case, in order to reduce the interaction between these virtual metals 16 and the antenna 13, especially the two endpoints of the longitudinal direction (longitudinal direction) where the electromagnetic wave energy is denser when the antenna 13 receives and transmits electromagnetic waves (or the first and last ends of the antenna 13) ) near the virtual metal 16 interacts with the antenna 13, and the distribution of the virtual metal 16 on the back surface of the substrate 11 often still has some restrictions. For example, in some embodiments, the distance between these virtual metals 16 and the antenna 13 near the two ends of the antenna 13 receiving and/or emitting electromagnetic waves is relatively long, while the distance between these virtual metals 16 and the antenna 13 is near other parts of the antenna. The distance is relatively short; in some embodiments, the distribution of these virtual metals 16 is relatively sparse near the two ends of the antenna 13 receiving and/or emitting electromagnetic waves, and the distribution of these virtual metals is relatively sparse near other parts of the antenna 13. dense; and in some embodiments, the respective areas of these dummy metals 16 near the two ends of the antenna 13 receiving and/or emitting electromagnetic waves are relatively small, while the respective areas of these dummy metals 16 near other parts of the antenna 13 are relatively large. Of course, in other embodiments, the restrictive condition can be further expanded to include that the distribution of the part of the virtual metal 16 closer to the antenna 13 is relatively sparse or the size is smaller, or the restrictive condition can be further expanded to be closer to the antenna 13. The part of virtual metal 16 farther away is more densely distributed or larger in size, or the above-mentioned restriction conditions can be used in combination. In addition, except that the shapes of these dummy metals 16 can be different from each other in different embodiments, even in the same embodiment, each dummy metal 16 can be different from each other, the present invention can elastically adjust the dummy metals 16 in different embodiments according to actual needs 16. For example, in order to simplify the manufacturing process and mechanical structure, the shape of any dummy metal 16 can be a quadrangle or even a rectangle. Here, Figures 2C to 2E briefly show three possible variations.

Further, the distances between the virtual metals 16 and the antenna 13 and the distances between the virtual metals 16 and the longitudinal ends of the antenna 13 are often proportional to the wavelength of the electromagnetic wave that the antenna 13 is designed to receive and/or emit. This is because near the two ends of the antenna, the range where the electromagnetic wave intensity is stronger when receiving and/or transmitting electromagnetic waves is proportional to the wavelength of the electromagnetic wave that the antenna 13 is designed to receive and/or transmit. Even, the gaps between these dummy metals 16 can also be proportional to the wavelength of the electromagnetic waves that the antenna 13 is designed to receive and/or emit, so as to reduce adverse effects such as electromagnetic wave diffraction. .

In addition, or in order to use these dummy metals 16 to enhance the mechanical strength and meet the requirements of the manufacturing process, or to reduce the influence of the induced current generated during the antenna receiving and/or transmitting electromagnetic waves, some embodiments of the present invention It is better to make the respective areas of each dummy metal 16 as small as possible, that is, when the total area of these dummy metals 16 used is fixed, it tends to make a large number of dummy metals 16 with small areas instead of using a few large ones. area of virtual metal 16. In addition, the spacing between the dummy metals 16 and the antenna 13 and even the spacing between the dummy metals 16 can also be adjusted, although the spacing has a minor impact on enhancing the mechanical strength and meeting the requirements of the manufacturing process. In some embodiments of the present invention, the distance between these dummy metals 16 and the antenna 13 should be as small as possible (but not smaller than the wavelength that the antenna 13 is designed to handle electromagnetic waves). In some embodiments of the present invention, the distance between adjacent dummy metals 16 is as small as possible.

For example, when the antenna 13 is designed to receive and/or transmit electromagnetic waves with a frequency between about 80 GHz and 650 GHz, the possible distribution restrictions of these dummy metals 16 on the back surface of the substrate 11 include at least one of the following: The gap between the dummy metals 16 is greater than about 50 microns, and the length of any side of any one of the dummy metals 16 is greater than about 150 microns. Here, the shape of any dummy metal 16 can be a quadrilateral, such as a rectangle or a square.

In addition, the use of the dummy metal 16 has another benefit: reducing the damage (like is an erroneous signal with additional noise). This is because, the electromagnetic wave that antenna 13 will receive and emit (especially will receive) will not only appear in the space near the antenna 13 and the back surface of the substrate 11, and these electromagnetic waves may always appear on the back surface of the substrate 11 instead of the antenna 13. part. Therefore, even if a similar shared potential reference 14 and/or a dielectric used to electrically isolate the circuit 12 from the outside world are used, the circuit 12 will be affected to some extent because the actual design cannot completely electrically isolate the circuit 12 . For example, when the area of the circuit 12 is larger than the area of the antenna 11 and the back surface of the substrate 11 is facing the traveling direction of the electromagnetic wave, it can be simply considered that only part of the circuit 11 is shielded by the antenna 11, that is, a part of the circuit 11 is shielded by the antenna 11. 11 is more susceptible to the influence caused by electromagnetic waves being transmitted from the back surface of the substrate 11 to the circuit through the substrate 11 . In any case, if there is a dummy metal 16 around the antenna 13 on the back surface of the substrate 11, due to the influence of the shielding effect (shielding effect) of conductive materials such as metal, electromagnetic waves are transmitted from parts other than the antenna 13 on the back surface of the substrate 11 to the The probability of the circuit 12 located on the front surface of the substrate 11 and the corresponding side effects can be reduced, so that the present invention of placing the circuit 12 and the antenna 13 on different surfaces of the same substrate 11 has better performance. Here, it must be emphasized that the present invention does not need to limit the number, shape, position, etc. depends on the relative configuration of the shared potential reference 14).

In addition, since the antenna 13 may cause a non-negligible induced current (induced current) when receiving and/or emitting electromagnetic waves, and then cause such as affecting the operation of the circuit 12 and/or the antenna 13 or causing a discharge (discharge) Loss of damage dummy metal 16 etc. Therefore, some embodiments of the present invention also include a plurality of ground balls to guide induced currents appearing on one or more surfaces of the die 11 (whether it is the front surface, the back surface or the side surface) away from the integrated circuit and the antenna. Die, like the printed circuit board where the die that directs the induced current to the integrated circuit and wires sits. Here, different ground balls are respectively connected to different parts of one or more surfaces of the die. In different embodiments of the present invention, these grounding balls are either evenly distributed on the front surface of the substrate 11, or evenly distributed on the back surface of the substrate 11, or distributed on the front surface of the substrate 11, or distributed on the back surface of the substrate 11, Or it may be distributed on the part where the induced current is denser and stronger on the substrate 11 when the antenna 13 receives and/or emits electromagnetic waves. Furthermore, the distribution of these ground balls on one or more surfaces of the substrate 11 can also be used to reinforce the mechanical strength of the entire integrated circuit and the crystal grains of the antenna. The present invention does not need to limit the specific details of these ground balls, such as whether the ground balls are gold bumps, solder balls or other conductive materials, or the number, shape and distribution of these ground balls, etc. Wait. Here, FIGS. 3A-3B schematically show two sample structures of two integrated circuit and antenna dies using the ground ball 17 .

FIG. 4A and FIG. 4B show the basic flow of the integrated circuit and antenna chip integration method proposed by the present invention. First, as step a shown in step block 401, the distribution of circuits on the front surface of the substrate and the distribution of antennas on the back surface of the substrate, a plurality of dummy metals, and a plurality of ground balls on one or more surfaces of the substrate are set. Here, it can be set according to the configuration of similar crystal grains in the database content, or the configuration of these virtual metals and these ground balls can be randomly arranged after placing the circuit and antenna in the middle of the front surface and the back surface respectively, Or set according to the content discussed above for such grains. The present invention does not need to strictly limit how to set in step a, because subsequent steps will be modified and adjusted. Next, as step b shown in step block 402, simulate the electromagnetic field and current distribution on the antenna, the virtual metal, and the earth when the antenna receives and transmits electromagnetic waves. In this simulation process, it is necessary to deal with the electromagnetic fields and currents faced by these grounded balls and these virtual metals, especially to calculate the distribution of induced currents. Then, as step c shown in step block 403, the distribution of the antenna, the virtual metal and/or the grounding ball is adjusted according to the simulation result. Here, adjusting the direction basically means adjusting the distribution of the dummy metals and the ground balls to a position where the induced current can be effectively guided away from the grain (or adjusted to the position where the induced current is the most intense). Next, step b and step c (or step block 402 and step block 403 ) are repeated until the electromagnetic field and current distribution on the antenna, these virtual metals and these grounding balls meet requirements. In other words, after step block 402 , as shown in decision block 404 , it is judged whether the simulation result is acceptable, such as whether the distribution or influence of the generated induced current is within an acceptable range. If possible, the simulation result of block 402 is directly used as the actual configuration of the die for producing such an integrated circuit and antenna. If not, then proceed to step block 403 and step block 402 in order, and then proceed to judgment block 404 again with the new simulation result, and decide whether to use it as the actual configuration or according to the judgment result. Step block 403 and step block 402 are performed in sequence again until an acceptable result is obtained (or these steps are stopped and repeated when an acceptable result is obtained). It must be noted that in this method, the circuit and the antenna are electrically connected to the shared potential reference, the dummy metals surround the antenna and are separated from the antenna, and different ground balls are respectively connected to different parts of one or more surfaces of the substrate. Moreover, the adjustments made in step c must allow the distribution of these dummy metals on the back surface of the substrate (such as the density of dummy metals) to meet the requirements of mechanical strength and related manufacturing processes.

In addition, since the configuration of the antenna is related to the wavelength of the electromagnetic wave it is designed to receive and/or transmit, the intensity of the electromagnetic wave expected to be received and/or transmitted, and even how the antenna and the circuit transmit electromagnetic signals to each other, The adjustment of the antenna will affect many factors. In some embodiments of the present invention, in steps b and c, the antenna is fixed and only the virtual metals and the ground balls are repeatedly adjusted until they meet the requirements. Further, since these ground ball configurations are related to the connection between such integrated circuits and antenna dies and printed circuit boards, the adjustment of these ground balls will not only affect the distribution of the induced current. In some embodiments of the present invention, in steps b and c, the antenna and the grounding balls are fixed and only the virtual metals are repeatedly adjusted until they meet the requirements. Whether these grounding balls and antennas need to be adjusted is optional depending on actual conditions, and the present invention is not limited thereto.

Generally speaking, the part that can be adjusted in step c includes but is not limited to the following: the size of at least one virtual metal, the shape of at least one virtual metal, the distance between at least two virtual metals, at least the distance between the virtual metal and the antenna The distance, the position of these virtual metals around the antenna, the number and position of these virtual metals. Generally speaking, the adjustments that can be made in step c include but are not limited to the following: make the size of these virtual metals as small as possible, make the distance between these virtual metals as small as possible, and make the part farther away from the antenna The size of these dummy metals is large, the size of these dummy metals near the antenna is small, and the distance between the dummy metal and both ends of the antenna is as large as possible. Generally speaking, the adjustments that can be made in step c include but are not limited to the following: making the gap between these virtual metals proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit, making these virtual metals and the longitudinal direction of the antenna two The distance between the endpoints is proportional to the wavelength of the electromagnetic wave the antenna is designed to receive and/or transmit, and the gap between the virtual metals is proportional to the wavelength of the electromagnetic wave the antenna is designed to receive and/or transmit.

Since the key point of this method is to first simulate and find out the place where the induced current is more intense (or the part where the electromagnetic field strength is stronger), and then adjust the position, distribution, and Quantity or shape, etc., whereby either the generation of such induced current distributions is eliminated or the induced currents that would cause problems are directed away. Therefore, the chip to be integrated in this method can directly use various details and possible changes of the chip for integrating the circuit and the antenna discussed above.

For example, the method does not need to limit the details of both circuits and antennas at all. For example, this method may place the antenna in the middle of the back surface, or place the antenna around the back surface, or allow the antenna to overlap the circuit in a direction perpendicular to the front surface and the back surface, or may The antenna is separated from the circuit in a direction perpendicular to the front surface and the back surface. For example, this method may design the size of the antenna in proportion to the wavelength of the electromagnetic waves that the antenna is designed to receive and emit, and may allow the antenna to occupy a larger proportion of the back surface of the substrate when the antenna is a resonant antenna . For example, this method may use the potential reference that the circuit uses regardless of whether there is an antenna as a shared potential reference, or may place the shared potential reference inside the substrate between the antenna and the circuit, or may use the shared potential The reference is placed on the front surface, or the potential sharing reference can be placed on the side surface of the substrate, and or the potential sharing reference can be placed inside the substrate. For example, the method may set the proportion of the area of the back surface shared by the antenna and the dummy metals and the common distribution on the back surface according to the mechanical strength of the die and the manufacturing process of the die.

For example, this method may make the distance between the virtual metals near the two ends of the antenna receiving and/or emitting electromagnetic waves relatively far from the antenna, and the distance between the virtual metals near other parts of the antenna and the antenna be relatively small. close, or the distribution of these virtual metals near the two ends of the antenna receiving and/or transmitting electromagnetic waves may be sparser, and the distribution of these virtual metals near other parts of the antenna may be denser, or these virtual metals may be distributed in The area of these virtual metals near the two ends of the antenna receiving and/or emitting electromagnetic waves is small, and the area of these virtual metals near other parts of the antenna is larger, or the area of the virtual metals near the antenna can be made larger. The distribution of some of these dummy metals is relatively sparse and the distribution of these dummy metals is denser in the part farther away from the antenna, or the size of the dummy metals in the part closer to the antenna can be made smaller and closer to the antenna. The farther part of these virtual metals has a larger size.

For example, this method can allow these grounding balls to be evenly distributed on the front surface of the substrate, or can allow these grounding balls to be evenly distributed on the back surface of the substrate, or can allow these grounding balls to be distributed on the front surface of the substrate, or can allow these The ground balls are distributed on the back surface of the substrate, or these ground balls can be distributed on one or more surfaces of the substrate (whether it is the front surface, the back surface or the side surface), or these ground balls can be distributed on the antenna when receiving and/or transmitting The part where the induced current is denser and stronger on the substrate during electromagnetic waves. In addition, the method does not limit the details of the ground balls, for example gold bumps or solder balls can be used as the ground balls.

For example, when the antenna is designed to receive and/or transmit electromagnetic waves with a frequency between about 80 GHz and 650 GHz, that is, when it is designed to deal with terahertz-gigahertz waves that have become popular in recent years, the steps The simulation and adjustment made in b and step may include at least one of the following: the gap between these virtual metals is about greater than 50 microns, the length of any side of any virtual metal is about greater than 150 microns, and any virtual metal is allowed to be greater than about 150 microns. The shape of the metal is a quadrilateral, and the shape of any one of the virtual metals is a rectangle.

Incidentally, generally speaking, when the frequency of the electromagnetic wave to be processed is greater than about 60 GHz, the advantages of using the integrated circuit and antenna chip and the integration method proposed by the present invention begin to be obvious. For example, if the substrate material used is gallium arsenide with a dielectric coefficient of about 12.9, the antenna is designed to receive and/or emit electromagnetic waves with a frequency of about 100 GHz (wavelength of about 3000 micrometers), and the antenna length Then it is about 417.6 mm. Considering that in general commercial applications, the length of each side of the die (die) is about 2 mm, and the size of the antenna is about one-third to one-half of the size of the die (considering the integration The mechanical strength, heat dissipation, electromagnetic interference and subsequent packaging manufacturing process of the crystal grain of the circuit and the antenna, etc.). It can be easily found that when the frequency of the electromagnetic wave is higher than about 60 GHz or even higher, the various benefits of the integrated circuit and antenna chip proposed by the present invention will start to become apparent.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the technical content disclosed above to make some changes or modify them into equivalent embodiments with equivalent changes. Technical Essence of the Invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (29)

1. A crystal grain of integrated circuit and antenna, characterized in that comprising: a substrate having a front surface and a back surface; a circuit located on the front surface; an antenna on the back surface; and A shared potential reference is electrically connected to the circuit and the antenna. 2. The grain according to claim 1, further comprising at least one of the following: The shared potential reference is located on the front surface; the shared potential reference is located on the side surface of the substrate; the shared potential reference is internal to the substrate; and The shared potential reference is located inside the substrate between the antenna and the circuit. 3. The die according to claim 1, wherein the shared potential reference is a potential reference used by the circuit regardless of whether the antenna is present or not. 4. The chip according to claim 1, characterized in that: the position of the antenna on the back surface can be elastically adjusted and does not have to be located in the middle of the back surface or perpendicular to the front surface with the circuit. The direction of the surface and the back surface overlap each other. 5. The die according to claim 1, wherein the size of the antenna is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and emit. 6. The crystal grain according to claim 1, wherein the ratio of the antenna to the area of the back surface is larger when the antenna is a resonant antenna, and is more unlimited when the antenna is a non-resonant antenna. . 7. The die of claim 1, comprising a plurality of dummy metals on the back surface surrounding the antenna but separated from the antenna. 8. The crystal grain according to claim 7, characterized in that: the area ratio of the antenna and the dummy metal occupying the back surface and the distribution on the back surface depend on at least the following two points: the crystal The mechanical strength of the grain is related to the manufacturing process of the grain. 9. The crystal grain according to claim 7, wherein the distribution limit of the dummy metal on the back surface at least includes one of the following: The dummy metal is farther away from the antenna near both ends of the antenna for receiving and/or emitting electromagnetic waves, and the dummy metal is closer to the antenna near other parts of the antenna; The dummy metals are sparsely distributed near both ends of the antenna for receiving and/or emitting electromagnetic waves, and the dummy metals are densely distributed near other parts of the antenna; and The respective areas of the dummy metals near the two ends of the antenna receiving and/or emitting electromagnetic waves are relatively small, while the respective areas of the dummy metals near other parts of the antenna are relatively large. 10. The crystal grain according to claim 7, wherein the distribution limit of the dummy metal on the back surface at least comprises one of the following: The part of the dummy metal closer to the antenna is sparsely distributed, while the part of the dummy metal farther away from the antenna is denser; and A portion of the dummy metal closer to the antenna has a smaller size, while a portion of the dummy metal farther away from the antenna has a larger size. 11. The crystal grain according to claim 7, wherein the distribution limit of the dummy metal on the back surface at least comprises one of the following: The distance between the virtual metal and the antenna is proportional to the wavelength of the electromagnetic waves that the antenna is designed to receive and/or emit; The distance between the virtual metal and the two ends in the longitudinal direction of the antenna is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit; and The gap between the dummy metals is proportional to the wavelength of the electromagnetic waves that the antenna is designed to receive and/or transmit. 12. The die according to claim 7, wherein when the antenna is designed to receive and/or transmit electromagnetic waves with a frequency between 80 GHz and 650 GHz, the dummy metal is on the back surface Distribution constraints include at least one of the following: The gap between the dummy metals is greater than 50 microns; Any one side of the dummy metal is greater than 150 microns; and The shape of any one of the virtual metals is a quadrilateral or a rectangle. 13. The die according to claim 7, comprising a plurality of ground balls, and different ground balls are respectively connected to different parts of the dummy metal. 14. The grain according to claim 13, characterized in that it comprises at least one of the following: The ground balls are evenly distributed on the front surface; said grounding balls are evenly distributed on the back surface; The grounding balls are distributed on the front surface; The ground balls are distributed on the negative surface; The ground balls are distributed on one or more side surfaces of the substrate; and The grounding balls are distributed on the part of the substrate where the induced current is denser and stronger when the antenna receives and/or emits electromagnetic waves. 15. The die according to claim 13, wherein the ground balls are gold bumps or solder balls. 16. A method for integrating a circuit and an antenna in the same die, characterized in that it comprises: a. set the circuit distribution on the front surface of the substrate and the distribution of the antenna on the back surface of the substrate and a plurality of dummy metals and a plurality of ground balls on one or more surfaces of the substrate; b. Simulating the electromagnetic field and current distribution on the antenna, the virtual metal, and the earth ground when the antenna receives and transmits electromagnetic waves; c. adjusting the distribution of the antenna, the virtual metal and the grounding ball according to the simulation results; d. Repeat step b and step c until the electromagnetic field and current distribution on the antenna, the virtual metal and the grounding earth meet the requirements; Here, the circuit and the antenna are electrically connected to a shared potential reference; Here, the dummy metal surrounds the antenna and is separated from the antenna; Here, different ground balls are respectively attached to different portions of one or more surfaces of the substrate. 17. The method according to claim 16, characterized in that it comprises fixing the antenna in step b and step c and only repeatedly adjusting the virtual metal and the grounding ball until they meet requirements. 18. The method according to claim 16, characterized in that it comprises fixing the antenna and the ground ball in steps b and c and only repeatedly adjusting the virtual metal until it meets the requirements. 19. The method according to claim 16, wherein step c comprises adjusting at least one of the following: the size of at least one virtual metal, the shape of at least one virtual metal, the distance between at least two virtual metals , the distance between at least one virtual metal and the antenna, the position of a part of the virtual metal around the antenna, and the quantity and position of the virtual metal. 20. The method according to claim 16, wherein step c comprises at least one of the following: making the size of the virtual metal as small as possible, allowing the distance between the virtual metals to be as small as possible, Let the size of the part of the dummy metal that is farther away from the antenna be larger, make the size of the part of the dummy metal that is closer to the antenna smaller, and let the dummy metal and the first and last ends of the antenna be smaller. end distance as large as possible. 21. The method of claim 16, comprising at least one of the following: Place the antenna in the middle of the back surface: placing the antenna around the back surface; allowing the antenna to overlap the circuit in a direction perpendicular to the front surface and the back surface; separating the antenna from the circuit in a direction perpendicular to the front surface and the back surface; sizing the antenna in proportion to the wavelengths of electromagnetic waves the antenna is designed to receive and transmit; and When the antenna is a resonant antenna, the antenna occupies a larger proportion of the back surface. 22. The method of claim 16, comprising at least one of the following: using the potential reference used by the circuit regardless of the presence or absence of the antenna as the shared potential reference; positioning the shared potential reference within the substrate between the antenna and the circuit; placing the shared potential reference on the front surface; placing the shared potential reference on a side surface of the substrate; and The shared potential reference is placed inside the substrate. 23. The method according to claim 16, characterized in that it includes setting the ratio of the area of the back surface shared by the antenna and the dummy metal according to the mechanical strength of the crystal grain and the manufacturing process of the crystal grain and the common Distribution pattern on the back surface. 24. The method according to claim 16, comprising adjusting the distribution of the dummy metal on the back surface according to at least one of the following: The part of the dummy metal near the two ends of the antenna receiving and/or emitting electromagnetic waves is far away from the antenna, and the part of the dummy metal near other parts of the antenna is relatively close to the antenna; The distribution of the dummy metals near the two ends of the antenna receiving and/or emitting electromagnetic waves is relatively sparse, and the distribution of the dummy metals near other parts of the antenna is relatively dense; and The respective areas of the dummy metals near both ends of the antenna receiving and/or emitting electromagnetic waves are relatively small, and the respective areas of the dummy metals near other parts of the antenna are relatively large. 25. The method according to claim 16, comprising adjusting the distribution of the dummy metal on the back surface according to at least one of the following: The distribution of the virtual metal in the part closer to the antenna is relatively sparse, and the distribution of the virtual metal in the part farther from the antenna is denser; and The size of the dummy metal is smaller at the part closer to the antenna, and the size of the dummy metal is larger at the part farther away from the antenna. 26. The method according to claim 16, comprising adjusting the distribution of the dummy metal on the back surface according to at least one of the following: The gap between the virtual metals is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or transmit; The distance between the virtual metal and the two ends in the longitudinal direction of the antenna is proportional to the wavelength of the electromagnetic wave that the antenna is designed to receive and/or emit; and The gap between the dummy metals is proportional to the wavelength of the electromagnetic waves that the antenna is designed to receive and/or transmit. 27. The method of claim 16, comprising at least one of the following: allowing the ground ball to be evenly distributed on the front surface of the part where the antenna is located; allowing said grounding balls to be evenly distributed on the back surface of the portion where said dummy metal is located; distributing said grounding balls on the front surface of the portion where the antenna is located; distributing the ground balls on the back surface of the part where the dummy metal is located; and Let the grounding balls be distributed on the part where the induced current on the virtual metal is denser and stronger when the antenna receives and/or emits electromagnetic waves. 28. The method of claim 16, comprising using gold bumps or solder balls as the ground balls. 29. The method according to claim 16, wherein when the antenna is designed to receive and/or transmit electromagnetic waves with a frequency between 80 GHz and 650 GHz, step b and step c further include at least one of the following one: allowing the dummy metals to have a gap greater than 50 microns between each other; have either side of any such virtual metal be greater than 150 microns; and Let the shape of any one of the virtual metals be a quadrilateral or a rectangle.