Bonded backing plate and housing for use in bump-bonded chip assemblies

Abstract

A method for forming an electronic chip assembly includes bonding a first metal plate to a first surface of a substrate to form a backing plate. A first cavity is created extending through the substrate to extend into at least the first metal plate. An electronic component is bonded to the substrate such that the electronic component is located within the first cavity. A second metal plate containing a second cavity is positioned on the second surface of the substrate over the first cavity such that the electronic component is enclosed within the first and second cavities by the first and second metal plates.

Description

Technical Field

[0001] Embodiments of the present invention as presently claimed relate to electronic chip assemblies and corresponding methods.

Background Art

[0002] Quantum computers often include quantum bits (qubits) formed as part of a quantum qubit chip of quantum components. The quantum chip may be part of a quantum chip assembly, in which the quantum qubit chip is bonded to a quantum interposer chip, which is then bonded to a printed circuit board (PCB). This assembly may include a metal plate known as a "penny" attached to the opposite face of the PCB, enclosing the quantum chip within a microwave cavity defined by the penny.

[0003] In forming a quantum chip assembly, two pennies are placed adjacent to the quantum chip and attached to the PCB on opposite faces of the PCB. The quantum chip is placed within a hole formed in the PCB. In manufacture, first the quantum qubit chip is indium bump bonded to the quantum interposer chip, and then the quantum interposer chip is bonded to the PCB. During this procedure, a metal backing plate is screwed to the PCB to provide a flat stable surface and enable the bonding to be performed accurately and reproducibly. After the quantum interposer chip has been bonded to the PCB, the metal backing plate is removed, and then the two pennies are bonded to the PCB.

Summary of the Invention

[0004] The currently claimed aspects of the present invention provide a method for forming an electronic chip assembly. A first metal plate is bonded to a first surface of a substrate to form a backing plate. A first cavity is created that extends through the substrate so as to extend at least to the first metal plate. Electronic components are bonded to the substrate so that the electronic components are located within the first cavity. A second metal plate containing a second cavity is positioned on the second surface of the substrate, over the first cavity, so that the electronic components are enclosed within the first and second cavities by the first and second metal plates.

[0005] According to some embodiments, creating a first cavity involves creating a first cavity within a first metal plate. According to some embodiments, the first and second cavities form an electromagnetic resonance chamber with a wavelength cutoff to remove electromagnetic radiation having wavelengths below the wavelength cutoff. According to some embodiments, the electronic component comprises a qubit chip and a quantum interposer chip bonded to the qubit chip, the quantum interposer chip being bonded to a substrate. According to some embodiments, bonding the quantum interposer chip to the substrate is performed after bonding the first metal plate to a first surface of the substrate.

[0006] According to some embodiments, the substrate is either a printed circuit board (PCB) or a laminate. According to some embodiments, the first and second metal plates include aluminum or copper. According to some embodiments, the electronic components are separated from the first and second metal plates by an insulator when they are enclosed within the first and second cavities by the first and second metal plates. According to some embodiments, this insulator is a gas or a vacuum.

[0007] According to some embodiments, bonding a first metal plate to a first surface of a substrate includes forming a seal between the first metal plate and the substrate. According to some embodiments, this seal includes an indium seal. According to some embodiments, the seal is formed in a groove in at least one of the first metal plate or the substrate. According to some embodiments, the first cavity has a cross-section in the substrate that is the same as or smaller than the cross-section in the first metal plate.

[0008] Another aspect of the present invention, as currently claimed, provides a method for forming an electronic chip assembly. A first metal plate is bonded to a first surface of a substrate to form a backing plate. A first cavity is created that extends through the substrate so as to extend at least to the first metal plate. Multiple electronic components are bonded to the substrate, each electronic component including a quantum interposer chip and a quantum bit chip, such that a qubit chip is located within the first cavity. A second metal plate containing a second cavity is placed on the second surface of the substrate, above the first cavity, such that the electronic components are enclosed within the first and second cavities by the first and second metal plates.

[0009] According to some embodiments, creating a first cavity involves creating a first cavity that extends within a first metal plate.

[0010] Another aspect of the present invention, as currently claimed, provides an electronic chip assembly comprising a substrate. A first metal plate is positioned on a first surface of the substrate to form a backing plate, and a first cavity extends through the substrate into the first metal plate. At least one electronic component is positioned within the first cavity. A second metal plate containing a second cavity is positioned above the first cavity such that at least one electronic component is enclosed within the first cavity and the second cavity by the first and second metal plates.

[0011] According to some embodiments, at least one electronic component comprises a plurality of electronic components. According to some embodiments, the first cavity has a cross-section in the substrate that is the same as or smaller than the cross-section in the first metal plate. According to some embodiments, each at least one electronic component comprises a quantum interposer chip and a qubit chip bonded to the quantum interposer chip.

[0012] In addition to the present disclosure, the methods of operation and function of combinations of relevant elements and parts of the structure, as well as the economics of manufacture, will become further apparent when the following description and the appended claims are considered with reference to the appended drawings. All of these form part of this specification, and similar reference numerals designate corresponding parts in various drawings. However, it should be clearly understood that these drawings are for illustrative and explanatory purposes only and are not intended as definitions of the limitations of the present invention. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of an electronic chip assembly according to one embodiment. [Figure 2A] This is a schematic diagram showing a top view of an electronic chip assembly containing a single electronic component within a cavity, according to one embodiment. [Figure 2B] This is a schematic diagram showing a top view of an electronic chip assembly containing multiple electronic components within a cavity, according to one embodiment. [Figure 3A] This figure shows a process flow of a method for forming an electronic chip assembly according to some embodiments. [Figure 3B] This figure shows a process flow of a method for forming an electronic chip assembly according to some embodiments. [Figure 3C] This figure shows a process flow of a method for forming an electronic chip assembly according to some embodiments. [Modes for carrying out the invention]

[0014] According to some embodiments, instead of using a separate backing plate on the substrate for bonding the quantum interposer chip to the substrate, and then removing the backing plate and placing a penny to form a microwave cavity for the quantum chip, the backing plate is not removed. Instead, a single plate is used as both the backing plate and one of the pennies. According to some embodiments, the single backing plate may include a suitable notch for the qubit chip, and this notch in the plate forms a cavity that becomes part of the entire cavity formed by the penny. Thus, a single backing plate is used as both the backing plate and the penny. Doing so has the advantage of preventing the substrate from warping after manufacturing and reduces processing in some embodiments. A net advantage is the improved reliability of the bump bond between the substrate and the interposer in some embodiments.

[0015] Figure 1 is a schematic diagram of an electronic chip assembly 100 according to some embodiments. The electronic chip assembly 100 includes a substrate 120. The substrate 120 may be, for example, a PCB or a laminate or both, and may be formed of a resin material.

[0016] The electronic chip assembly 100 may further include a first metal plate 110 positioned on a first surface 122 of a substrate 120 to function as a backing plate. The first metal plate 110 may be attached to the substrate 120 by screws 170. The electronic chip assembly 100 may include a groove 180 in the substrate 120, the first metal plate 110, or both. The groove 180 may be filled with a sealing material 185, such as In, to provide a seal between the first metal plate 110 and the substrate 120.

[0017] The first cavity 150 extends through the substrate 120 to at least the first metal plate 110. In some embodiments, the first cavity 150 extends into the first metal plate 110.

[0018] In some embodiments, the first cavity 150 may have a cross-section in the substrate 120 that is the same as or smaller than the cross-section in the first metal plate 110. In this way, a portion of the first cavity 150 in the first metal plate 110 does not cut through the substrate 120, thus improving the stability when the material is bonded to the substrate 120.

[0019] In some embodiments, the electronic chip assembly 100 may include at least one electronic component 130. At least one electronic component 130 is located within the first cavity 150. Each of the at least one electronic component 130 may be a quantum interposer chip 134 or a qubit chip 132 or both. Each of the at least one electronic component 130 may include a quantum interposer chip 134 and a qubit chip 132 containing one or more qubits coupled to the quantum interposer chip 134. The qubit chip 132 may be bonded to the quantum interposer chip 134, for example, via a bump bond 136. The quantum interposer chip 134 may be bonded to the substrate 120, for example, via a bump bond 136. The bump bond 136 may be formed of a material containing, for example, In. In some embodiments, the qubit chip 132 may be directly bonded to the substrate 120, for example, if the electronic component 130 does not include a quantum interposer chip 134.

[0020] The electronic chip assembly 100 may include a second metal plate 140. The second metal plate 140 may include a second cavity 160 positioned above the first cavity 150 such that at least one electronic component 130 is enclosed within the first and second cavities (150, 160) by the first and second metal plates (110, 140). The first and second metal plates (110, 140) may be formed of, for example, aluminum or copper.

[0021] The first cavity and the second cavity (150, 160) together form the entire cavity that functions as a microwave cavity, and the size of the entire cavity determines the wavelength of the microwave resonance within the entire cavity. The first cavity 150 and the second cavity 160 may form an electromagnetic resonance chamber having a wavelength cut-off in order to remove wavelengths below the wavelength cut-off. Note that most, if not all, external radiation is removed not by a cut-off mechanism, but by surrounding the device using a bottom plate and a top plate (forming the sealed cavities together).

[0022] FIG. 1 shows an embodiment in which a single electronic component 130 is enclosed within the first cavity and the second cavity (150, 160). FIG. 2A is a schematic top view showing an embodiment in which the qubit chip 132 of a single electronic component 130 is enclosed within the first cavity and the second cavity (150, 160). Alternatively, as shown in the schematic top view of FIG. 2B, two or more qubit chips 132 may be enclosed within the first cavity and the second cavity (150, 160).

[0023] FIGS. 3A, 3B, and 3C show a process flow of a method for forming an electronic chip assembly, such as the electronic chip assembly 100 of FIG. 1, according to some embodiments.

[0024] As shown in FIG. 3A, a first metal plate 110 is attached to the first surface 122 of the substrate 120 to form a backing plate on the substrate 120. The first metal plate 110 may be formed of, for example, aluminum or copper. The first metal plate 110 may be formed to have planes on both sides. The flatness of the surface of the first metal plate 110 may be sufficient so that the bonding of the electronic component 130 to the substrate 120 is improved. In some embodiments, the first metal plate 110 may be attached to the substrate 120 such that there is no gap between the first metal plate 110 and the substrate 120. In some embodiments, the plane of the first metal plate 110 may be precision ground.

[0025] The substrate 120 may be formed of a resin material or a laminated material or both, and may be a PCB. The first metal plate 110 may be attached to the first surface 122 of the substrate 120 by, for example, screws 170 or pins.

[0026] As shown in FIG. 3A, a first cavity 150 extending through the substrate 120 is created so as to extend at least into the first metal plate 110. The first cavity 150 may be formed through the substrate 120, for example, by chemical etching or by a mechanical process such as cutting or punching. The first cavity 150 may be formed so as to extend into the first metal plate 110. For example, the first cavity 150 may be formed so as to extend into the first metal plate 110 by, for example, chemical etching or by a mechanical process.

[0027] In some embodiments, the first cavity 150 may be formed to have a cross-section in the substrate 120 that is the same as or smaller than the cross-section in the first metal plate 110. In this way, a portion of the first cavity 150 within the first metal plate 110 does not cut under the substrate 120, thus improving the stability during the bonding process of the electronic component 130 to the second surface 124 of the substrate 120.

[0028] According to some embodiments, the attachment of the first metal plate 110 to the first surface 122 of the substrate 120 may include forming a seal between the first metal plate 110 and the substrate 120. This seal may be formed by forming a seal material 185 within a groove 180 formed in one of the first metal plate 110 and the substrate 120. The seal material 185 may include, for example, In.

[0029] As shown in Figure 3B, the electronic component 130 is then bonded to the second surface 124 of the substrate 120. The electronic component 130 may include a quantum interposer chip 134 and a qubit chip 132. The quantum interposer chip 134 and the qubit chip 132 may be formed from different or the same material. For example, both the quantum interposer chip 134 and the qubit chip 132 may be formed from semiconductor material. One or more qubits may be formed on the qubit chip 132. According to some embodiments, one or more microwave generation structures may be formed on the quantum interposer chip 134 to generate microwaves at a desired wavelength.

[0030] As shown in Figure 3B, the quantum interposer chip 134 is attached to the qubit chip 132. According to some embodiments, the quantum interposer chip 134 may be attached to the qubit chip 132 by a bonding process. For example, the quantum interposer chip 134 may be bonded to the qubit chip 132 via a bump bond 136. In this case, the bump bond 136 may be heated so that it bonds the quantum interposer chip 134 to the qubit chip 132.

[0031] As shown in Figure 3A, the quantum interposer chip 134 is attached to the substrate 120. According to some embodiments, the quantum interposer chip 134 may be attached to the substrate 120 by a bonding process. For example, the quantum interposer chip 134 may be bonded to the substrate 120 via a bump bond 136. In this case, the bump bond 136 may be heated so that it bonds the quantum interposer chip 134 to the substrate 120. According to some embodiments, the quantum interposer chip 134 may be bonded to a qubit chip 132 before the quantum interposer chip 134 is bonded to the substrate 120.

[0032] As shown in Figure 3C, the second metal plate 140, which includes the second cavity 160, is positioned on the second surface of the substrate 120, above the first cavity 150, so that the quantum interposer chip 134 and the qubit chip 132 are enclosed within the first cavity and the second cavity (150, 160) by the first metal plate and the second metal plate (110, 140). When the quantum interposer chip 134 and the qubit chip 132 are enclosed within the first cavity and the second cavity (150, 160) by the first metal plate and the second metal plate (110, 140), the quantum interposer chip 134 and the qubit chip 132 may be separated from the first metal plate and the second metal plate (110, 140) by an insulator 190. The insulator 190 may be, for example, a gas or a vacuum.

[0033] The second metal plate 140 may be attached to the substrate 120. For example, the second metal plate 140 may be attached to the substrate 120 using screws, for example. An indium gasket may be used to attach the first metal plate 110, the second metal plate 140, or both, to the substrate 120.

[0034] Figure 3C shows a single electronic component 130 enclosed within a first cavity and a second cavity (150, 160) by a first metal plate and a second metal plate (110, 140). Alternatively, as shown in Figure 2B, multiple electronic components 130 may be enclosed within a first cavity and a second cavity (150, 160) by a first metal plate and a second metal plate (110, 140).

[0035] According to some embodiments, the aforementioned devices and methods offer several advantages. A single backing plate is used as both the backing plate and the penny. Doing so has the advantage, in some embodiments, of preventing the substrate from warping after manufacturing and reducing processing. A net advantage, in some embodiments, is the improved reliability of the bump bond between the substrate and the interposer.

[0036] The descriptions of various embodiments of the present invention are presented for illustrative purposes only and are not intended to be exhaustive, nor are they intended to limit the disclosed embodiments. Many changes and modifications that do not deviate from the scope and spirit of the described embodiments will be apparent to those skilled in the art. The terminology used herein has been selected to best describe the principles of the embodiments, their practical applications, or any technical improvements beyond the technology available on the market, or to enable those else skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for forming an electronic chip assembly, To form a backing plate, a first metal plate is bonded to a first surface of the substrate, To create a first cavity that extends through the substrate so as to extend at least to the first metal plate, The electronic component is bonded to the substrate such that the qubit chip contained in the electronic component is located within the first cavity, The electronic component is enclosed within the first cavity and the second cavity by the first metal plate and the second metal plate, by which the second metal plate is placed on the second surface of the substrate above the first cavity. A method for creating a first cavity within a first metal plate.

2. The method according to claim 1, wherein the first cavity and the second cavity form an electromagnetic resonant chamber having a wavelength cutoff in order to remove electromagnetic radiation having a wavelength below the wavelength cutoff.

3. The method according to claim 1 or 2, wherein the electronic component comprises a qubit chip and a quantum interposer chip bonded to the qubit chip, and the quantum interposer chip is bonded to the substrate.

4. The method according to claim 3, wherein the bonding of the quantum interposer chip to the substrate is performed after the first metal plate is bonded to the first surface of the substrate.

5. The method according to any one of claims 1 to 4, wherein the substrate is one of a printed circuit board (PCB) or a laminate.

6. The method according to any one of claims 1 to 5, wherein the first metal plate and the second metal plate include aluminum or copper.

7. The method according to claim 6, wherein the first metal plate and the second metal plate contain copper.

8. The method according to any one of claims 1 to 7, wherein the electronic component is separated from the first metal plate and the second metal plate by an insulator when the electronic component is enclosed within the first cavity and the second cavity by the first metal plate and the second metal plate.

9. The method according to claim 8, wherein the insulator is a gas or a vacuum.

10. The method according to any one of claims 1 to 9, wherein bonding the first metal plate to the first surface of the substrate includes forming a seal between the first metal plate and the substrate.

11. The method according to claim 10, wherein the seal includes an indium seal.

12. The method according to claim 10 or 11, wherein the seal is formed in a groove in at least one of the first metal plate or the substrate.

13. The method according to any one of claims 1 to 12, wherein the first cavity has a cross-section in the substrate that is the same as or smaller than the cross-section in the first metal plate.

14. A method for forming an electronic chip assembly, To form a backing plate, a first metal plate is bonded to a first surface of the substrate, To create a first cavity that extends through the substrate so as to extend at least to the first metal plate, Bonding a plurality of electronic components to a substrate such that a qubit chip is located within the first cavity, wherein each electronic component includes a quantum interposer chip and the qubit chip, The method includes arranging the second metal plate, which contains the second cavity, on the second surface of the substrate above the first cavity, such that the electronic component is enclosed within the first cavity and the second cavity by the first metal plate and the second metal plate, A method for creating a first cavity such that the first cavity extends within the first metal plate.

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