CN105280727A - Microwave internal matching power transistor matching capacitor and manufacturing method thereof - Google Patents

Abstract

The invention discloses a microwave internal matching power transistor matching capacitor and a manufacturing method thereof, and relates to the technical field of capacitors and manufacturing methods thereof. The capacitor includes the MIM capacitive component that has completed the front process of the internal matching capacitor. The MIM capacitive component includes a substrate, the upper surface of the substrate is provided with a metal lower electrode, and the substrate is provided with a lead-out through hole. The lower surface of the substrate is provided with a lead-out electrode of the lower metal electrode, and a part of the lead-out electrode of the lower metal electrode is electrically connected to the lower metal electrode through the lead-out through hole. The capacitor has the characteristics of high temperature resistance, good frequency performance, small volume, simple manufacturing process and low cost.

Description

Microwave internal matching power transistor matching capacitor and manufacturing method thereof

technical field

The invention relates to the technical field of capacitors and manufacturing methods thereof, in particular to a microwave internal matching power transistor matching capacitor and a manufacturing method thereof.

Background technique

In order to avoid excessive loss after adding the internal matching network and adversely affect the overall performance of the device, it is required that the microwave loss of the internal matching capacitor and internal matching inductance must be small. As the operating frequency increases, the inductance of the bonding wire will also increase, and the microwave loss will increase, which is unfavorable to the frequency performance of microwave devices, especially for the source ground wire and common source of field effect transistors with a common source structure. The length of the base bonding wire of a bipolar transistor with a base structure has a great influence on the microwave performance. In order to minimize the inductance of the ground lead, the patent document with the application number CN201310126712.3 discloses a MIM capacitor and its manufacturing method (the structure of the capacitor is shown in Figure 1), which uses a ground electrode drawn from the upper surface Methods The grounding of the metal electrode of the capacitor is achieved by bonding wires, and the effect of the bonding wires on the microwave performance of the device will be more significant with the increase of the operating frequency of the device. This is not conducive to further improving the frequency performance of the matching power transistor in the microwave, and also wastes the area of the wafer.

The internal matching capacitors of traditional microwave internal matching power transistors generally adopt MOM (metal-oxide-metal) capacitor structure, and some use MOS (metal-oxide-semiconductor) structure, because the metal lower electrodes are all conductive , so there is no need to use bonding wires to realize the grounding of the lower electrode of the capacitor metal. However, the cost of MOM capacitors is high, and the microwave performance and high-temperature stability of MOS capacitors are not as good as those of MOM capacitors. Therefore, in order to enable the internal matching device to work at high temperatures, an internal matching capacitor with high temperature resistance has been developed (see patent CN201310126712.3). In order to avoid the reaction of metal and substrate at high temperature to affect the stability of the capacitor, the developed internal matching capacitors for high temperature work generally use high-stability materials such as silicon carbide or sapphire as substrate materials, rather than general For semiconductor materials, due to the poor conductivity of silicon carbide and sapphire, the ground electrode of the capacitor must be drawn from the upper surface of the capacitor, which not only occupies the area of the wafer, but also the grounding of the capacitor must be realized through bonding wires. It is detrimental to the microwave performance of internally matched power transistors.

Contents of the invention

The technical problem to be solved by the present invention is to provide a microwave internal matching power transistor matching capacitor and its manufacturing method. The capacitor prepared by the method has the characteristics of high temperature resistance, good frequency performance, small volume, simple manufacturing process and low cost. .

In order to solve the above technical problems, the technical solution adopted by the present invention is: a microwave internal matching power transistor matching capacitor, which is characterized in that: it includes a capacitor assembly on the MIM that has completed the front process of the internal matching capacitor, and the capacitor assembly on the MIM includes a substrate , the upper surface of the substrate is provided with a metal lower electrode, the substrate is provided with a lead-out through hole, the lower surface of the substrate is provided with a metal lower electrode lead-out electrode, and a part of the metal lower electrode lead-out electrode passes through It is electrically connected with the metal lower electrode through the lead-out through hole.

A further technical solution is: the MIM upper capacitor assembly includes a substrate, the upper surface of the substrate is provided with a metal lower electrode, the outer side of the metal lower electrode is wrapped with an insulating medium layer, and the upper surface of the insulating medium layer is provided with metal top electrode.

A further technical solution is that: the metal lower electrode extraction electrode includes a metal seed layer on the upper layer and a metal thickening layer on the lower surface of the metal seed layer.

A further technical solution is: the metal seed layer is made of titanium-gold or titanium-tungsten-gold, the metal thickening layer is made of gold, and the substrate is silicon carbide or sapphire.

The invention also discloses a method for manufacturing a matching capacitor of a microwave internal matching power transistor, which is characterized in that the method includes the following steps:

1) Preparation of capacitor components on MIM: through the front-side processing technology of capacitors, MIM capacitor components with internal matching capacitors are produced. The capacitor components on MIM include a substrate, and the upper surface of the substrate is provided with a metal lower electrode, and a metal lower electrode The outer side of the insulating medium layer is wrapped with an insulating medium layer, and the upper surface of the insulating medium layer is provided with a metal upper electrode;

2) Thinning: Thinning the substrate of the capacitor component on the MIM;

3) Backside photolithography: use photolithography to form a mask for etching the through holes on the backside of the thinned substrate;

4) Corrosion of the lead-out through hole on the back: At the position of the substrate corresponding to the lower metal electrode of the MIM capacitor, the lead-out through hole of the metal lower electrode of the MIM capacitor is etched on the back, and the photolithographic mask is removed after the lead-out through hole is corroded;

5) Forming the lead-out electrode: forming the lead-out electrode of the metal lower electrode of the MIM capacitor on the back of the substrate where the lead-out through hole is formed, so that the lead-out electrode of the metal lower electrode is in direct contact with the metal lower electrode to form an electrical connection.

A further technical solution is: the steps of preparing the capacitor assembly on the MIM are as follows: first, the substrate material is cleaned, and then the metal lower electrode of the MIM capacitor is formed on the substrate through photolithography and metallization processes, and then PECVD or LPCVD is used to The method deposits the insulating dielectric layer of the capacitor, and then forms the metal upper electrode of the MIM capacitor through photolithography and metallization processes.

A further technical solution is: before step 2), the method also includes a step of bonding the sheet, specifically, bonding the front side of the capacitor component on the MIM with a sapphire sheet.

A further technical solution is: after step 5), the method further includes a step of removing the sheet, specifically, removing the sapphire sheet bonded to the front of the capacitor component on the MIM.

A further technical solution is: the step 5) is specifically:

Back sputtering metal: sputtering a layer of metal seed layer on the back of the substrate where the lead-through hole is formed;

Metal backside electroplating: Through the electroplating thickening method, a metal thickening layer is formed on the metal seed layer, and the metal seed layer and the metal thickening layer together constitute the metal lower electrode lead-out electrode of the MIM capacitor.

A further technical solution is: after the step 5), a scribing step is also included. Specifically, the MIM capacitors on the entire wafer are divided by a dicing knife according to the scribing lanes to form individual MIM capacitors.

The beneficial effect of adopting the above technical solution is: in order to avoid the adverse effect of the internal matching capacitor grounding bonding wire on the frequency performance, the present invention omits the bonding wire and replaces it with a capacitor grounding lead out from the back of the substrate. Compared with the original structure of the internal matching capacitor, it not only saves the upper surface area of the wafer occupied by the lower electrode lead-out electrode of the wafer, but also improves the microwave frequency performance of the internal matching capacitor, and is also conducive to reducing the size of the internal matching capacitor. Realizing more internal matching capacitors on the same wafer reduces the manufacturing cost of the internal matching capacitors, and also omits capacitor ground bonding wires, which simplifies the process. That is to say, the present invention is not only beneficial to the high-temperature stable operation of the internal matching device, but also helps to improve the frequency performance of the device, reduce the volume of the device, reduce the labor intensity and work difficulty of manual mounting and bonding, and reduce the cost of the internal matching capacitor. This also reduces the overall cost of the internal matching device.

In order to achieve the above goals, in the manufacturing process of the internal matching capacitor, after the front process of the internal matching capacitor is completed, a backside thinning process of the silicon carbide or sapphire substrate is added, the purpose is to prevent the via hole from the back of the internal matching capacitor from being too thin. Deep, there is metal discontinuity, and the electrical connection of the lower electrode of the capacitor metal cannot be realized, and a process of photolithography, corrosion, and metallization of the back-leading through-hole is added. However, the photolithography and corrosion process for the lower electrode of the high-temperature internal matching capacitor to lead out from the upper surface are omitted, and the metal electrode for the metal lower electrode to be led out from the upper electrode is omitted. In the subsequent manual assembly process, the internal A metal bond wire job is matched to the lower electrode (ground electrode) of the capacitor. Therefore, the process is simplified as a whole, the manufacturing cost is reduced, and the microwave performance of the internal matching microwave power transistor is improved; at the same time, due to the reduction of the area of the internal matching capacitor, the volume of the internal matching power transistor can be further reduced, which is conducive to the realization of the device miniaturization.

Description of drawings

Fig. 1 is the structural representation of the MIM capacitor in the application number CN201310121712.3;

Fig. 2 is a schematic diagram of the structure of the capacitor assembly on the MIM where the capacitor of the present invention has completed the front process;

Fig. 3 is a schematic structural view of the capacitance of the present invention after the back substrate is thinned;

Fig. 4 is the mask pattern after drawing the through hole photolithography on the back side of the capacitor according to the present invention;

Fig. 5 is a schematic structural view of the lead-through hole on the back of the capacitor according to the present invention after it has been etched clean and the mask has been removed;

Fig. 6 is the structure schematic diagram after metal sputtering on the back side of the capacitor according to the present invention;

Fig. 7 is a structural schematic diagram of the electroplated backside of the capacitor according to the present invention;

Among them: 1, substrate 2, metal lower electrode 3, insulating medium layer 4, metal lead-out electrode 5 in the prior art, metal upper electrode 6, mask 7, lead-out through hole 8, metal seed layer 9, metal thickening Layer 10, metal lower electrode lead-out electrode.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the following description, a lot of specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described here, and those skilled in the art can do it without departing from the meaning of the present invention. By analogy, the present invention is therefore not limited to the specific examples disclosed below.

Embodiment one

As shown in Fig. 7, the present invention discloses a microwave internal matching power transistor matching capacitor, the capacitor includes a capacitor component on the MIM that has completed the front process of the internal matching capacitor, the capacitor component on the MIM includes a substrate 1, and the capacitor component on the MIM includes a substrate 1. The substrate 1 is a stable material that does not easily react with metal electrodes at high temperature, such as silicon carbide or sapphire. The upper surface of the substrate 1 is provided with a metal lower electrode 2 , the outside of the metal lower electrode 2 is wrapped with an insulating medium layer 3 , and the upper surface of the insulating medium layer 3 is provided with a metal upper electrode 5 . The substrate 1 is provided with a lead-out through hole 7, and the lower surface of the substrate 1 is provided with a metal lower electrode lead-out electrode, and a part of the metal lower electrode lead-out electrode 10 passes through the lead-out through hole 7 and the The metal lower electrode 2 is electrically connected. The metal lower electrode extraction electrode includes a metal seed layer 8 on the upper layer and a metal thickening layer 9 on the lower surface of the metal seed layer 8 . The metal seed layer 8 is made of titanium-gold or titanium-tungsten-gold, and the metal thickening layer 9 is made of gold.

Embodiment two

The invention also discloses a method for manufacturing a matching capacitor of a microwave internal matching power transistor, and the method includes the following steps:

1) First, clean the stable substrate material, such as silicon carbide or sapphire, which does not undergo obvious alloy reaction with the metal lower electrode 2 at high temperature; then form the metal lower electrode of the MIM capacitor on the substrate 1 through photolithography and metallization processes Electrodes; then PECVD or LPCVD is used to deposit the insulating dielectric layer 3 of the capacitor; in order to improve the compactness and stability of the dielectric layer, the insulating dielectric layer is subjected to dense annealing at a high temperature of 800°C-850°C; then photolithography and The metal upper electrode 5 of the MIM capacitor is formed by the metallization process; in order to avoid mechanical damage to the insulating dielectric layer during scribing, the insulating dielectric layer at the scribing line is etched clean; the structure shown in FIG. 2 is formed.

2) Bonding: The front side of the MIM capacitor wafer that has completed the above process is bonded to a sapphire sheet. The purpose is to prevent the wafer from being too thin after the substrate of the MIM capacitor wafer is thinned. Pieces cracked.

3) Thinning: The back of the substrate 1 of the MIM capacitor wafer is thinned, and the MIM capacitor wafer is reduced to 50 μm-120 μm by chemical mechanical polishing, as shown in Figure 3, the purpose is to avoid subsequent pass Hole technology is too difficult.

4) Backside photolithography: In order to complete the lead-out of the lower metal electrode of the MIM capacitor from the back, so as to avoid the influence of the inductance of the bonding wire drawn from the front on microwave performance, this photolithography is used to form a mask 6 for etching the through-holes on the back, as shown in Figure 4 shown.

5) Corrosion of the through hole 7 on the back side: the lead-out through hole 7 of the lower electrode of the MIM capacitor is etched on the back of the MIM capacitor wafer substrate 1 at the position corresponding to the metal lower electrode 2. This through hole is to corrode the thinned silicon carbide Or sapphire substrates, instead of corroding semiconductor silicon or gallium arsenide substrates like in the chip process, so the etchant used in the process will be different from the general corrosion of semiconductor substrates. If the MIM capacitor uses a sapphire substrate, it is necessary to avoid corrosion of the sapphire chip used for bonding the chip during corrosion. The mask 6 is removed after the via hole is etched, as shown in FIG. 5 .

6) Metal sputtering on the back: In order to form the metal lower electrode lead-out electrode 10 on the back of the MIM capacitor, a layer of metal titanium-gold or titanium-tungsten-gold is sputtered on the back of the substrate where the through hole is formed, and the lining of the through hole is formed. A layer of metal seed layer 8 is sputtered on the bottom and back to serve as the metal electrode seed layer on the back.

7) Electroplating on the back of the metal: through the thickening method of electroplating, the metal thickening layer 9 is formed on the metal seed layer, and the metal seed layer and the metal thickening layer together constitute the metal lower electrode lead-out electrode of the MIM capacitor .

8) Remove the sheet: remove the sapphire sheet attached to the front of the MIM capacitor wafer in step 2), and at this time, the production of the through hole on the back of the MIM capacitor of the present invention is completed.

9) Scribing: Divide the MIM capacitors on the entire wafer according to the instructions of the scribing lane with a dicing knife to form the finished products of individual MIM capacitors as shown in Figure 7.

So far, the fabrication of the MIM capacitor of the present invention has been completed. This process method can also be extended to the MIM capacitor manufacturing process using semiconductor silicon or gallium arsenide substrate materials, which is also effective for improving its frequency performance.

It should be noted that Figure 1 shows the structure of the original high-temperature-resistant MIM capacitor. For clarity, the scribing track of the capacitor and half of the adjacent capacitor are shown. Figure 2 and other diagrams show only one MIM capacitor and its scribing track because of the same simple repetition period. The capacitor values in FIG. 1 are the same as those in FIG. 7 . It can be clearly seen that the wafer area occupied by the present invention is significantly reduced, and more MIM capacitors can be produced on the same wafer.

In order to avoid the adverse effect of internal matching capacitor grounding bonding wires on frequency performance, the present invention omits the bonding wires and instead uses capacitance grounding to lead out from the back of the substrate. Compared with the original structure of the internal matching capacitor, it not only saves the upper surface area of the wafer occupied by the lower electrode lead-out electrode of the wafer, but also improves the microwave frequency performance of the internal matching capacitor, and is also conducive to reducing the size of the internal matching capacitor. Realizing more internal matching capacitors on the same wafer reduces the manufacturing cost of the internal matching capacitors, and also omits capacitor ground bonding wires, which simplifies the process. That is to say, the present invention is not only beneficial to the high-temperature stable operation of the internal matching device, but also helps to improve the frequency performance of the device, reduce the volume of the device, reduce the labor intensity and work difficulty of manual mounting and bonding, and reduce the cost of the internal matching capacitor. This also reduces the overall cost of the internal matching device.

In order to achieve the above goals, in the manufacturing process of the internal matching capacitor, after the front process of the internal matching capacitor is completed, a backside thinning process of the silicon carbide or sapphire substrate is added, the purpose is to prevent the via hole from the back of the internal matching capacitor from being too thin. Deep, there is metal discontinuity, and the electrical connection of the lower electrode of the capacitor metal cannot be realized, and a process of photolithography, corrosion, and metallization of the back-leading through-hole is added. However, the photolithography and corrosion process for the lower electrode of the high-temperature internal matching capacitor to lead out from the upper surface are omitted, and the metal electrode for the metal lower electrode to be led out from the upper electrode is omitted. In the subsequent manual assembly process, the internal A metal bond wire job is matched to the lower electrode (ground electrode) of the capacitor. Therefore, the process is simplified as a whole, the manufacturing cost is reduced, and the microwave performance of the internal matching microwave power transistor is improved; at the same time, due to the reduction of the area of the internal matching capacitor, the volume of the internal matching power transistor can be further reduced, which is conducive to the realization of the device miniaturization.

Claims (10)

1. mesh power transistor matching capacitance in a microwave, it is characterized in that: comprise complete interior matching capacitance front technique MIM on capacitance component, the upper capacitance component of MIM comprises substrate (1), the upper surface of described substrate (1) is provided with lower metal electrode (2), described substrate (1) is provided with draws through hole (7), the lower surface of described substrate (1) is provided with lower metal electrode extraction electrode (10), and a part for described lower metal electrode extraction electrode (10) is electrically connected with described lower metal electrode (2) through described extraction through hole (7).

2. mesh power transistor matching capacitance in microwave as claimed in claim 1, it is characterized in that: on described MIM, capacitance component comprises substrate (1), the upper surface of described substrate (1) is provided with lower metal electrode (2), the outside of lower metal electrode (2) is enclosed with insulating medium layer (3), and the upper surface of described insulating medium layer (3) is provided with electrode of metal (5).

3. mesh power transistor matching capacitance in microwave as claimed in claim 1, is characterized in that: described lower metal electrode extraction electrode (10) comprises the metal seed layer (8) being positioned at upper strata and the metal thickening layer (9) being positioned at metal seed layer (8) lower surface.

4. mesh power transistor matching capacitance in microwave as claimed in claim 3, it is characterized in that: the making material of described metal seed layer (8) is titanium-Jin or titanium tungsten-Jin, the making material of described metal thickening layer (9) is gold, and described substrate (1) is carborundum or sapphire.

5. the manufacture method of mesh power transistor matching capacitance in microwave, is characterized in that described method comprises the steps:

1) the upper capacitance component preparation of MIM: by electric capacity front processing technology, capacitance component on the MIM of the interior matching capacitance of making, on described MIM, capacitance component comprises substrate (1), the upper surface of described substrate (1) is provided with lower metal electrode (2), the outside of lower metal electrode (2) is enclosed with insulating medium layer (3), and the upper surface of described insulating medium layer (3) is provided with electrode of metal (5);

2) thinning: the substrate (1) of capacitance component on MIM is carried out thinning back side;

3) back side photoetching: substrate (1) the upper employing photoetching after thinning forms the mask (6) that etched backside draws through hole (7);

4) corrosion of through hole (7) is drawn at the back side: in the position of the lower metal electrode (2) of the corresponding MIM capacitor of substrate, the back side erodes away the extraction through hole (7) of the lower metal electrode of MIM capacitor, removes photo etched mask (6) after drawing through hole (7) corrosion;

5) extraction electrode is formed: forming the lower metal electrode extraction electrode (10) of the substrate back formation MIM capacitor of drawing through hole (7), lower metal electrode extraction electrode (10) directly being contacted with lower metal electrode (2), forms electrical connection.

6. the manufacture method of mesh power transistor matching capacitance in microwave as claimed in claim 5, it is characterized in that, the step that on described MIM prepared by capacitance component is as follows: first by clean for substrate (1) material clean, then on substrate, the lower metal electrode (2) of MIM capacitor is formed by photoetching and metallization process, adopt the insulating medium layer (3) of PECVD or LPCVD method deposited capacitances subsequently, then formed the electrode of metal (5) of MIM capacitor by photoetching and metallization process.

7. the manufacture method of mesh power transistor matching capacitance in microwave as claimed in claim 5, it is characterized in that, described method is in step 2) before also comprise the step of bonding die, concrete, the front of capacitance component on MIM and a sapphire sheet are bonded together.

8. the manufacture method of mesh power transistor matching capacitance in microwave as claimed in claim 7, it is characterized in that, described method also comprises the step of sheet after step 5), concrete, will be bonded in the sapphire sheet removal in capacitance component front MIM on.

9. the manufacture method of mesh power transistor matching capacitance in microwave as claimed in claim 5, it is characterized in that, described step 5) is specially:

Back spatter metal: forming substrate back sputtering layer of metal Seed Layer (8) of drawing through hole;

The metal back side is electroplated: the method thickeied by plating, and at metal seed layer (8) upper formation metal thickening layer (9), metal seed layer (8) and metal thickening layer (9) form the lower metal electrode extraction electrode (10) of MIM capacitor together.

10. the manufacture method of mesh power transistor matching capacitance in microwave as claimed in claim 5, it is characterized in that, also scribing steps is comprised after described step 5), concrete, MIM capacitor on whole wafer is separated by the instruction of dicing lane by saw blade, form MIM capacitor discrete one by one.