Hafnium nitride adhesive layer

Abstract

A novel hafnium nitride adhesive layer useful for the manufacture of semiconductor devices is disclosed. In particular, semiconductor devices such as thin-film transistors, which include one or more elements formed of metals having a high electron concentration, such as molybdenum, tungsten, nickel, ruthenium, cobalt, and their alloys, can be better bonded to the dielectric material on which the semiconductor device is formed using the present invention, and the adhesive layer can also function as a diffusion barrier.

Description

Technical Field

[0001] The present invention relates to the manufacture of semiconductors. More specifically, the present invention relates to an adhesive layer suitable for better attaching a semiconductor element made of a metal having a high electron concentration in a semiconductor device and a method of manufacturing such an adhesive layer.

Background Art

[0002] The practice of manufacturing known semiconductor devices uses various different materials to form transistor and other semiconductor device structures on substrates such as silicon. Depending on the semiconductor device being manufactured and, in some cases, the manufacturing technology, the materials used are selected for their atomic structure, electrical properties, physical chemistry, etc.

[0003] [[ID= sixteenth]]Most commonly, semiconductor devices are formed on a silicon substrate and a dielectric layer of silicon dioxide initially formed on the silicon substrate. Next, elements of the semiconductor device and metal interconnects between the devices are formed in layers on the dielectric and on each other as required.

[0004] Some materials that may be desired to be used to form elements of a semiconductor device are known not to adhere well to other materials used, such as silicon dioxide or other dielectric materials. When thin film transistors are manufactured, the difficulty of adhesion can be particularly problematic because factors such as the residual film stress, morphology, density, and mechanical properties of the film can cause separation of the manufactured elements from the dielectric layer or from each other.

[0005] To address those problems, it is known to use a suitable adhesive material as a layer between silicon dioxide (or other dielectric material) and the material forming a particular semiconductor element. Generally, the adhesive material must be carefully selected to be compatible with other materials used in the semiconductor manufacturing process and to withstand subsequent manufacturing processes that may include deposition, annealing, etc. without adversely affecting them.

[0006] While various adhesive materials are known, not all materials work with or are suitable for a wide range of materials selected to form different semiconductor devices.

[0007] It is desirable to have a novel adhesive material suitable for use in the manufacture of semiconductor devices, particularly in the manufacture of thin-film transistors. [Overview of the project] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide novel adhesive layers and materials that eliminate or mitigate at least one drawback of the prior art, as well as methods for producing such adhesive layers and materials. [Means for solving the problem]

[0009] According to a first aspect of the present invention, a novel thin-film transistor is provided, having a source, a drain, a metal oxide semiconductor extending between them, a gate dielectric on the metal oxide semiconductor, and a gate on the gate dielectric, the thin-film transistor comprising a dielectric material layer and a hafnium nitride layer formed in at least a first region of the dielectric material layer, wherein the source is a metal having a high electron concentration and is formed in the at least first region of the hafnium nitride, and the hafnium nitride functions as an adhesive layer between the source metal and the dielectric layer.

[0010] Preferably, the dielectric layer is SiO2, Si, Si3N4, etc. Also preferably, the metal is selected from the group including molybdenum, tungsten, nickel, ruthenium, cobalt, and / or alloys thereof.

[0011] According to another aspect of the present invention, a novel semiconductor device is provided which is formed on a dielectric, comprising at least one element formed from a metal having a high electron concentration, and comprising a hafnium nitride adhesive layer formed on the dielectric, wherein the at least one element formed from the metal is formed on the hafnium nitride adhesive layer.

[0012] A novel method for manufacturing a thin-film transistor in a dielectric is provided, comprising: step i) forming a hafnium nitride adhesive layer on at least a first region of the dielectric, wherein the adhesive layer is formed by atomic layer deposition; step ii) forming at least one of a source element and a drain element on the adhesive layer in at least the first region, wherein at least one of the source element and the drain element is formed from a metal having a high electron concentration; step iii) forming a metal oxide semiconductor layer between the source element and the drain element; step iv) forming a gate dielectric on the semiconductor layer; and step v) forming a gate on the gate dielectric.

[0013] The present invention provides novel adhesive layers and materials useful for the manufacture of semiconductor devices. In particular, semiconductor devices such as thin-film transistors, which include one or more elements formed of a metal having a high electron concentration, can be better bonded to the dielectric material on which the transistor is formed by using the present invention. [Brief explanation of the drawing]

[0014] Preferred embodiments of the present invention will be described merely as examples with reference to the accompanying drawings.

[0015] [Figure 1] A schematic diagram of a transistor composed of an adhesive layer according to one aspect of the present invention is shown. [Figure 2] A schematic diagram of another transistor composed of an adhesive layer according to one aspect of the present invention is shown. [Figure 3]A flowchart illustrating a method for constructing a transistor having an adhesive layer according to one aspect of the present invention is shown. [Modes for carrying out the invention]

[0016] For example, in the case of some semiconductor devices such as thin-film transistors disclosed in the published PCT patent application international publication 2023 / 285936 (Barlage et al., the contents of which are incorporated herein by reference), it has been found that metals with high electron concentration (hereinafter referred to as "MHECs"), such as ruthenium, molybdenum, tungsten, nickel, cobalt, and / or alloys of these MHECs, can be advantageously used as source and / or drain elements of the transistor.

[0017] However, it has been found that MHECs do not adhere well to common underlying dielectric materials (such as thermal SiO2, Si, Si3N4PEALD SiO2, and WTO SiO2) on which such transistors can be formed. Therefore, the inventors have demonstrated that hafnium nitride (HfN) can be successfully used as an adhesive layer to effectively bond the MHEC structure to a dielectric layer such as silicon dioxide. Specifically, they have shown that hafnium nitride functions to bond MHECs to dielectric materials such as silicon dioxide, thereby suppressing delamination and / or buckling of elements formed with MHECs in semiconductor devices.

[0018] Advantageously, hafnium nitride provides the desired adhesion properties to the MHEC and also acts as a diffusion barrier, preventing undesirable interactions between the MHEC and dielectric materials such as silicon dioxide or other dielectrics. In particular, the hafnium nitride layer suppresses the movement of oxygen from the dielectric layer to the MHEC element.

[0019] Another advantage of the present invention is that it simplifies the manufacturing process of the Barlage et al. thin-film transistors described above. In preferred embodiments, at least some structures of the Barlage et al. thin-film transistors are manufactured using atomic layer deposition (ALD), and in preferred embodiments, their gate dielectric is hafnium dioxide (HfO2) formed from a hafnium ALD precursor. This same precursor can also be used to form a desired hafnium nitride adhesive layer when combined with nitrogen as a reaction gas.

[0020] The overall manufacturing process can be simplified by using the same ALD precursor to form the desired adhesive layer and gate dielectric for thin-film transistors.

[0021] As a non-limiting example, a hafnium nitride (HfN) adhesive film was grown using a plasma-enhanced atomic layer deposition (PEALD) continuous flow ALD system, in this example, a Kurt J. Lesker ALD150-LX. The film was grown using a remotely inductively coupled plasma (13.56 MHz ICP, 0.6 kW, 60 sccm FG, 100 sccm Ar carriers) at a reactor pressure of 1.01 Torr.

[0022] Tetrakis(dimethylamino)hafnium (TDMAHf) and the forming gas (FG: 5%H2 + 95%N2) served as the Hf precursor and reaction plasma source, respectively. The process conditions for self-limiting HfN PEALD were characterized using in situ spectroscopic ellipsometry (M2000DI, JAWoollam). The growth rate per cycle (GPC) in the PEALD cycle on a planar Si substrate was 0.1 seconds of TDMAHf pulse, 12 seconds of precursor post-purge, 9 seconds of FG plasma exposure, and 5 seconds of plasma post-purge.

[0023] In this process, HfN grown at an ampoule temperature of 78 °C and a substrate temperature of 200 °C obtained a GPC of approximately 1.08 Å (0.108 nm) / cycle.

[0024] FIG. 1 shows a thin film transistor 20 formed in a dielectric layer 24 and including a source 28, a drain 32, a semiconductor layer 36 formed between the source 28 and the drain 32, a gate dielectric 40 formed on the semiconductor layer 36, and a gate 44 formed on the gate dielectric 40. As can be seen from the figure, a hafnium adhesion layer 48 is formed in the dielectric layer 24 before the source 28 is formed in the dielectric layer 24, and the adhesion layer 48 acts to strengthen the adhesion of the source 28 to the dielectric layer 24.

[0025] FIG. 2 shows another thin film transistor 60, and components similar to those shown in FIG. 1 are denoted by the same reference numerals. In the transistor 60, an adhesion layer 48 is formed in the dielectric layer 24 to strengthen the adhesion of both the source 28 and the drain 32 to the dielectric layer 24.

[0026] FIG. 3 shows a flowchart 200 of a method for manufacturing a thin film transistor according to one aspect of the present invention. The method starts at step 204 and forms a hafnium nitride adhesion layer on at least an area of a dielectric in which an MHEC element (source, drain, or both) is to be formed, and the adhesion layer is formed by atomic layer deposition using a suitable hafnium precursor gas. Next, the method proceeds to step 208 and forms a source element and / or a drain element on the hafnium nitride layer. Next, at step 212, a metal oxide semiconductor layer is formed between the source and the drain . Next, at step 216, a gate dielectric is formed on the metal oxide semiconductor. The method ends at step 220 where a gate is formed on the gate dielectric.

[0027] Preferably, the gate dielectric is hafnium dioxide and is formed with the same hafnium precursor used to form the adhesion layer in a plasma-assisted atomic layer deposition process using a forming gas containing nitrogen such as a mixture of 5% H and 95% N.

[0028] One unique aspect of Barlage et al.'s thin-film transistor is that it can be built on top of a conventional CMOS circuit or on top of other layers of Barlage et al.'s transistor to fabricate a stacked (3D) semiconductor device. In such cases, Barlage et al.'s transistor only requires the formation of a dielectric material layer on the underlying circuit (CMOS, Barlage et al., etc.), and then, using the present invention, an adhesive layer can be provided on that dielectric layer to subsequently form Barlage et al.'s transistor.

[0029] The above embodiments of the present invention are illustrative examples of the present invention, and those skilled in the art may modify and change these embodiments without departing from the scope of the present invention as defined solely by the appended claims.

Claims

1. A thin-film transistor having a source, a drain, a metal oxide semiconductor extending between them, a gate dielectric on the metal oxide semiconductor, and a gate on the gate dielectric, A dielectric material layer, A hafnium nitride layer formed in at least a first region of the dielectric material layer and Includes, The source is a metal having a high electron concentration and is formed in at least the first region of the hafnium nitride, the hafnium nitride functioning as an adhesive layer between the source metal and the dielectric layer, in a thin-film transistor.

2. The thin-film transistor according to claim 1, wherein the dielectric material is silicon dioxide.

3. The thin-film transistor according to claim 1, wherein the drain is also a metal having a high electron concentration and is formed on the hafnium nitride, and the hafnium nitride functions as an adhesive layer between the dielectric material and the source and drain, respectively.

4. The thin-film transistor according to claim 1, wherein the transistor includes a hafnium oxide gate dielectric, and the gate dielectric and the adhesive layer are formed by an atomic layer deposition process.

5. The thin-film transistor according to claim 4, wherein the hafnium oxide layer and the hafnium nitride layer are formed from the same atomic layer-deposited hafnium precursor except that different reaction gases are used.

6. The thin-film transistor according to claim 1, wherein the metal is selected from the group including molybdenum, tungsten, nickel, ruthenium, cobalt, and alloys thereof.

7. The thin-film transistor according to claim 3, wherein the metal is selected from the group including molybdenum, tungsten, nickel, ruthenium, cobalt, and alloys thereof.

8. A semiconductor device formed on a dielectric, comprising at least one element formed from a metal having a high electron concentration, and comprising a hafnium nitride adhesive layer formed on the dielectric, wherein the at least one element formed from metal is formed on the hafnium nitride adhesive layer.

9. The semiconductor device according to claim 8, wherein the metal having a high electron concentration is selected from the group including molybdenum, tungsten, nickel, ruthenium, cobalt, and alloys thereof.

10. A method for manufacturing a thin-film transistor on a dielectric, Step i) forming a hafnium nitride adhesive layer on at least a first region of the dielectric, wherein the adhesive layer is formed by atomic layer deposition, Step ii) forming at least one of a source element and a drain element on the adhesive layer in at least the first region, wherein at least one of the source element and the drain element is formed from a metal having a high electron concentration, Step iii) forming a metal oxide semiconductor layer between the source element and the drain element, Step iv) forming a gate dielectric on the semiconductor layer, Step v) forming a gate on the gate dielectric, Methods that include...

11. The method according to claim 10, wherein the adhesive layer is formed by plasma-assisted atomic layer deposition.

12. The method according to claim 10, wherein the gate dielectric is hafnium dioxide and is formed by atomic layer deposition.

13. The method according to claim 12, wherein the adhesive layer and the gate dielectric are formed from the same hafnium precursor.

14. The method according to claim 12, wherein the gate dielectric is formed by plasma-assisted atomic layer deposition.

15. The method according to claim 10, wherein the metal having a high electron concentration is selected from the group including molybdenum, tungsten, nickel, ruthenium, cobalt, and alloys thereof.

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