PHEMT device
By employing a multilayer metal structure design in the pHEMT device, the problems of electroplating spots and unstable ohmic contact resistance were solved, thereby improving the device's reliability and conductivity.
Patent Information
- Application Number
- CN202423300783.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-01-16
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Existing pHEMT devices suffer from plating defects and unstable ohmic contact resistance during ohmic contact layer formation, which makes the devices prone to burnout when operating at high current.
The design employs a multi-layer metal structure, including a first metal structure layer and a second metal structure layer with higher hardness. This prevents the metal in the first metal structure layer from diffusing into the second adhesion layer, and the formation of the second metal structure layer with higher hardness improves the surface roughness caused by the etching process, thereby reducing the generation of electroplating spots.
It effectively reduces the formation of electroplating spots, improves the stability and conductivity of ohmic contacts, and avoids device burnout caused by current concentration.
Smart Images
Figure CN223810082U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of semiconductor manufacturing, especially to a kind of pHEMT devices. BACKGROUND
[0002] The ohmic characteristic of pseudomorphic high electron mobility transistor (pHEMT) is crucial to the performance and reliability of the device, and good ohmic contact requires low contact resistance, uniform surface morphology and shallow internal diffusion of metal materials.
[0003] When the pHEMT device forms a metal interconnection structure including an ohmic contact layer, a first metal plating layer, and a second metal plating layer on the source region / drain region, the second metal plating layer is generated by electroplating. However, there is a problem of electroplating mottling during the electroplating of the second metal plating layer. The existence of electroplating mottling causes the current to concentrate in the point with smaller resistance when the device works under large current, which may even cause the device to burn out. In addition, there is also the problem of unstable ohmic contact resistance. SUMMARY
[0004] The purpose of the present utility model is to provide a pHEMT device to solve one or more problems in the prior art.
[0005] To solve the above problems, the present utility model provides a pHEMT device, comprising: a substrate and a metal interconnection structure formed on the substrate.
[0006] The metal interconnection structure comprises, from bottom to top, an ohmic contact layer, a first metal plating layer, and a second metal plating layer.
[0007] The first metal plating layer comprises, from bottom to top, a first adhesion layer, a first metal structure layer, a second metal structure layer, and a second adhesion layer. The second metal structure layer is used to block the diffusion of the metal of the first metal structure layer to the second adhesion layer to form an aggregation point on the surface of the first metal plating layer. The resistance of the first metal structure layer is smaller than that of the second metal structure layer, and the hardness of the second metal structure layer is greater than that of the first metal structure layer.
[0008] Optionally, in the pHEMT device, the material of the first metal structure layer comprises Au, and the material of the second metal structure layer comprises Pt.
[0009] Optionally, in the pHEMT device, the material of the second adhesion layer comprises Ti.
[0010] Optionally, in the pHEMT device, the thickness of the second adhesion layer is 2-100 nm, and the thickness of the second metal structure layer is 20-1000 nm.
[0011] Optionally, in the pHEMT device, the ohmic contact layer includes a third metal structure layer on the top layer, the first metal plating layer further includes a fourth metal structure layer between the first adhesion layer and the first metal structure layer, and the fourth metal structure layer is used to block diffusion of metal of the third metal structure layer to the first metal structure layer.
[0012] Optionally, in the pHEMT device, the third metal structure layer is made of Au, the first adhesion layer is made of Ti, and the fourth metal structure layer is made of Pt.
[0013] Optionally, in the pHEMT device, the first metal structure layer has a thickness greater than that of any one of the second metal structure layer, the first adhesion layer, the second adhesion layer, and the fourth metal structure layer.
[0014] Optionally, in the pHEMT device, the first adhesion layer has a thickness of 2-100 nm, and the fourth metal structure layer has a thickness of 20-1000 nm.
[0015] Optionally, in the pHEMT device, the substrate includes, from bottom to top, a semiconductor material substrate layer, a device structure layer, and a cap layer, a surface of the cap layer has a source region and a drain region, and the metal interconnection structure is formed on the drain region and / or a surface of the drain region.
[0016] Optionally, in the pHEMT device, the cap layer has a trapezoidal trench between the source region and the drain region, the trapezoidal trench exposes a surface of the device structure layer, and the pHEMT device further includes a gate structure extending from a bottom of the trapezoidal trench to outside of the trapezoidal trench away from the device structure layer.
[0017] In summary, the pHEMT device provided by the utility model, including: substrate and the metal interconnection structure formed on the substrate, the metal interconnection structure includes: the ohmic contact layer, the first metal plating layer and the second metal plating layer are stacked in turn from bottom to top, the first metal plating layer includes the first adhesion layer, the first metal structure layer, the second metal structure layer and the second adhesion layer are stacked in turn from bottom to top, the second metal structure layer is used to block the metal of the first metal structure layer diffuses to the second adhesion layer, the resistance of the first metal structure layer is less than the resistance of the second metal structure layer, the hardness of the second metal structure layer is greater than the hardness of the first metal structure layer, in the first metal plating layer, the second metal structure layer with higher hardness is formed to improve the surface roughness caused by subsequent etching process and block the first metal structure layer diffuses to the second adhesion layer and forms the gathering point on the surface of the first metal plating layer, so that the possibility of producing electroplating mottle when electroplating the second metal plating layer on the first metal plating layer can be reduced. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 Part structure schematic diagram of the pHEMT device provided by the utility model embodiment is provided;
[0019] Among them, the following is explained to each sign:
[0020] 10-substrate;20-ohmic contact layer;30-first metal plating layer;40-second metal plating layer;
[0021] 31-first adhesion layer;31-fourth metal structure layer;33-first metal structure layer;34-second metal structure layer;35-second adhesion layer. DETAILED DESCRIPTION
[0022] The pHEMT device provided by this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this utility model. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different proportions may be used in different drawings to show different emphases. It should be understood that relative terms such as "above," "below," "top," "bottom," and "upper" shown in the drawings can be used to describe the relationships between various elements. These relative terms are intended to cover different orientations of elements other than those depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element will now be below that element. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate logical or sequential relationships between the various components, elements, steps, etc.
[0023] The source / drain of a common pHEMT device typically includes an ohmic contact layer, a first metal plating layer, and a second metal plating layer. The first metal plating layer comprises a lower Ti layer, an Au layer, and an upper Ti layer stacked sequentially from bottom to top. The ohmic contact layer includes an Au layer at the top.
[0024] The intermediate Au layer in the first metal plating layer will diffuse upward to the Ti layer during the subsequent thermal process, causing Au accumulation on the surface of the first metal plating layer and small black spots to appear on the surface, thereby affecting the electroplating uniformity of the subsequent second metal plating layer.
[0025] Furthermore, after the first metal plating layer, a SiN layer is formed on the surface of the overall device structure, and then the SiN layer is etched to form trenches. The second metal plating layer is then formed in these trenches through an electroplating process. During the SiN layer etching process, the surface of the first metal plating layer is also partially etched, which can easily lead to plating spots when the second metal plating layer is subsequently formed on its surface.
[0026] The reason why the device has an unstable ohmic contact resistance is that Au in the top layer of the ohmic contact layer tends to diffuse into the device interior (towards the first metal plating layer) during the thermal process, thus causing the ohmic contact resistance to be unstable.
[0027] Based on the above findings, such as Figure 1 As shown, this embodiment provides a pHEMT device, including: a substrate 10 and a metal interconnect structure formed on the substrate 10;
[0028] The metal interconnection structure comprises, from bottom to top, an ohmic contact layer 20, a first metal plating layer 30, and a second metal plating layer 40;
[0029] The first metal plating layer 30 comprises, from bottom to top, a first adhesion layer 31, a first metal structure layer 33, a second metal structure layer 34, and a second adhesion layer 35. The second metal structure layer 34 is used to block the diffusion of the metal of the first metal structure layer 30 to the second adhesion layer 35 to form an aggregation point on the surface of the first metal plating layer 30. The resistance of the first metal structure layer 33 is smaller than that of the second metal structure layer 34, and the hardness of the second metal structure layer 34 is greater than that of the first metal structure layer 33.
[0030] The ohmic contact layer 20 and the first metal plating layer 30 are formed by an evaporation process, and the second metal plating layer 40 is formed by an electroplating process. By forming the second metal structure layer 34 with higher hardness, the surface roughness caused by subsequent etching processes is improved, and the diffusion of the first metal structure layer 34 to the second adhesion layer 35 is blocked, so that the possibility of electroplating mottling when electroplating the second metal plating layer 40 on the first metal plating layer 30 is reduced.
[0031] In this embodiment, the material of the first metal structure layer 33 is Au with a smaller resistance to improve the conductivity of the first metal plating layer 30. In other embodiments, the material of the first metal structure layer 33 can also be other metal materials with a smaller resistance. If the second adhesion layer 35 is directly formed on the surface of the first metal structure layer 33, since Au is relatively soft, when the second adhesion layer 35 is partially etched in the subsequent etching process, the exposed first metal structure layer 33 will also be damaged by etching, resulting in rough surface of the first metal structure layer 33. When the material of the first metal structure layer 33 is Au, the material of the second metal structure layer 34 can optionally include Pt, which has a higher hardness than Au and is not easily damaged by etching, so that the flatness of the surface of the first metal plating layer 30 is improved.
[0032] As described above, the combination of the first metal structure layer 33 and the second metal structure layer 34 not only ensures the conductivity of the first metal plating layer 30, but also improves the surface roughness caused by subsequent etching processes. In other embodiments, the second metal structure layer 34 can also be made of metal conductive materials such as Mo, Pd, Ta, and the like, which will not be described here.
[0033] In the embodiment, the material of the first adhesive layer 31 and the second adhesive layer 35 can be Ti. Ti has good adhesion and good Schottky characteristics. In other embodiments, the material of the first adhesive layer 31 and the second adhesive layer 35 can also be a conductive material with adhesion, such as TiW.
[0034] In the embodiment, the ohmic contact layer 20 includes a third metal structure layer on the top layer, and the first metal plating layer 30 further includes a fourth metal structure layer 32 between the first adhesive layer 31 and the first metal structure layer 33. The fourth metal structure layer 32 is used to block the metal of the third metal structure layer from diffusing to the first metal structure layer 33.
[0035] In the embodiment, the material of the third metal structure layer includes Au, and the material of the first adhesive layer 31 includes Ti. In the process of thermal processing, the two metals of Au and Ti are easy to diffuse to each other, and therefore, the Au in the third metal structure layer is easy to diffuse to the second metal plating layer 40, which can cause the unstable ohmic contact resistance of the device. The fourth metal structure layer 32 is added in the second metal plating layer 40, and the Au is further blocked from diffusing upward by the fourth metal structure layer 32, which can avoid the problem of unstable ohmic contact resistance of the device.
[0036] In other embodiments, the third metal structure layer can also include other metals that are easy to diffuse to the first adhesive layer 31, which will not be described herein.
[0037] In the embodiment, the fourth metal structure layer 32 can include Pt. In other embodiments, the fourth metal structure layer 32 can also be Mo, Pd, W, Ta, etc.
[0038] The thickness of each metal layer of the first metal plating layer 30 can be set as needed. Among them, the first metal structure layer 33 is the most important metal structure layer of the first metal plating layer 30, and the thickness thereof is preferably greater than that of any one of the second metal structure layer 34, the first adhesive layer 31, the second adhesive layer 35, and the fourth metal structure layer 32. Optionally, the thickness of the first metal structure layer 33 is 200-1500 nm, the thickness of the first adhesive layer 31 and the second adhesive layer 35 is 2-100 nm, and the thickness of the second metal structure layer 34 and the fourth metal structure layer 32 is 20-1000 nm. For example, in a specific example, the thicknesses of the first adhesive layer 31, the first fourth metal structure layer, the first metal structure layer 33, the second metal structure layer 34, and the second adhesive layer 35 are 50 nm, 100 nm, 900 nm, 500 nm, and 5 nm, respectively.
[0039] The pHEMT device provided by the embodiment can specifically include, from bottom to top, a semiconductor material substrate layer, a device structure layer, and a cap layer, the surface of the cap layer has a source region and a drain region, and the metal interconnection structure is formed on the drain region and / or the surface of the drain region. The device structure layer includes an electron supply layer, a channel layer, etc., and the specific film layer structure of the device structure layer of the pHEMT device is well known to those skilled in the art, and will not be described in detail here.
[0040] The cap layer can specifically be a GaAs layer. Further, the cap layer has a trapezoidal groove between the source region and the drain region, and the trapezoidal groove exposes the surface of the device structure layer, and the pHEMT device further includes a gate structure extending from the bottom of the trapezoidal groove to the outside of the trapezoidal groove away from the device structure layer.
[0041] In summary, the pHEMT device provided by the embodiment of the utility model, including: substrate and form on the substrate metal interconnection structure, the metal interconnection structure includes: from bottom to top sequentially stacked ohmic contact layer, first metal plating layer and second metal plating layer, the first metal plating layer includes from bottom to top sequentially stacked first adhesion layer, first metal structure layer, second metal structure layer and second adhesion layer, the resistance of first metal structure layer is less than the resistance of second metal structure layer, the hardness of second metal structure layer is greater than the hardness of first metal structure layer. In the first metal plating layer, by forming the second metal structure layer with higher hardness to improve the surface roughness caused by subsequent etching process and block the first metal structure layer to the second adhesion layer diffusion in the surface of the first metal plating layer forms the gathering point, so that the possibility of electroplating mottling when electroplating the second metal plating layer on the first metal plating layer can be reduced.
[0042] Further, a fourth metal structure layer is formed between the first adhesion layer and the first metal structure layer to block the diffusion of metal in the ohmic contact layer into the first metal plating layer, so that the problem of unstable ohmic contact resistance can be avoided.
[0043] It needs explanation, although the utility model has disclosed as above with preferable embodiment, however above embodiment is not used to limit the utility model. For any skilled person in the art, without departing from the utility model technical scheme range, can utilize above disclosed technical content to make many possible changes and modifications to the utility model technical scheme, or modify as equivalent variation equivalent embodiment. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the utility model without departing from the content of the utility model technical scheme, all still belong to the protection scope of the utility model technical scheme.
Claims
1. A pHEMT device, characterized by, The application relates to a metal interconnection structure and a pHEMT device. The metal interconnection structure comprises, from bottom to top, an ohmic contact layer, a first metal plating layer and a second metal plating layer. The first metal plating layer comprises, from bottom to top, a first adhesion layer, a first metal structure layer, a second metal structure layer and a second adhesion layer, the second metal structure layer is used for blocking the diffusion of metal in the first metal structure layer to the second adhesion layer to form a gathering point on the surface of the first metal plating layer, the resistance of the first metal structure layer is smaller than that of the second metal structure layer, and the hardness of the second metal structure layer is greater than that of the first metal structure layer. The material of the first metal structure layer comprises Au, and the material of the second metal structure layer comprises Pt.
2. The pHEMT device of claim 1, wherein, The material of the second adhesion layer comprises Ti.
3. The pHEMT device of claim 1, wherein, The thickness of the second adhesion layer is 2-100 nm, and the thickness of the second metal structure layer is 20-1000 nm.
4. The pHEMT device of claim 1, wherein, The ohmic contact layer comprises a third metal structure layer at the top layer, the first metal plating layer further comprises a fourth metal structure layer between the first adhesion layer and the first metal structure layer, and the fourth metal structure layer is used for blocking the diffusion of metal in the third metal structure layer to the first metal structure layer.
5. The pHEMT device of claim 1, wherein, The material of the third metal structure layer comprises Au, the material of the first adhesion layer comprises Ti, and the material of the fourth metal structure layer comprises Pt.
6. The pHEMT device of claim 5, wherein, The thickness of the first metal structure layer is greater than that of any one of the second metal structure layer, the first adhesion layer, the second adhesion layer and the fourth metal structure layer.
7. The pHEMT device of claim 5, wherein the p-type doped layer is formed of a p-type doped AlxGaι-xAs layer. The thickness of the first metal structure layer is 200-1500 nm, the thickness of the first adhesion layer is 2-100 nm, and the thickness of the fourth metal structure layer is 20-1000 nm.
8. The pHEMT device of claim 5, wherein, The substrate comprises, from bottom to top, a semiconductor material substrate layer, a device structure layer and a cap layer, the surface of the cap layer has a source region and a drain region, and the metal interconnection structure is formed on the drain region and / or the surface of the drain region.
9. The pHEMT device of claim 1, wherein, The cap layer has a trapezoidal groove between the source region and the drain region, and the trapezoidal groove exposes the surface of the device structure layer, and the pHEMT device further comprises a gate structure, the gate structure extends from the bottom of the trapezoidal groove to the outside of the trapezoidal groove in a direction away from the device structure layer.
10. The pHEMT device of claim 9, wherein,