阅读说明：本技术 具有横向半导体异质结的半导体器件和方法 (Semiconductor device and method with lateral semiconductor heterojunction ) 是由 李明洋 黄敬凯 李连忠 于 2018-09-20 设计创作，主要内容包括：用于形成具有横向半导体异质结的半导体器件的方法,包括在衬底上与第一金属电极相邻地形成横向半导体异质结的第一金属硫属化物层。第一金属硫属化物层包括与第一金属电极相同的金属,并且第一金属硫属化物层中的至少一些包括来自第一金属电极的金属。与第一金属硫属化物层相邻地形成横向半导体异质结的第二金属硫属化物层。与第二金属硫属化物层相邻地形成第二金属电极。第二金属硫属化物层包括与第二金属电极相同的金属。(A method for forming a semiconductor device having a lateral semiconductor heterojunction includes forming a first metal chalcogenide layer of the lateral semiconductor heterojunction on a substrate adjacent to a first metal electrode. The first metal chalcogenide layers include the same metal as the first metal electrodes, and at least some of the first metal chalcogenide layers include metal from the first metal electrodes. A second metal chalcogenide layer forming a lateral semiconductor heterojunction adjacent to the first metal chalcogenide layer. A second metal electrode is formed adjacent to the second metal chalcogenide layer. The second metal chalcogenide layer includes the same metal as the second metal electrode.)

1. A method for forming a semiconductor device having a lateral semiconductor heterojunction, the method comprising:

forming (205) a first metal chalcogenide layer (305) of a lateral semiconductor heterojunction on a substrate (315) adjacent to a first metal electrode (310), wherein the first metal chalcogenide layer (305) comprises the same metal as the first metal electrode (310) and at least some of the first metal chalcogenide layer (305) comprises metal from the first metal electrode (310);

a second metal chalcogenide layer (320) forming (210) a lateral semiconductor heterojunction adjacent to the first metal chalcogenide layer (305); and

forming (215) a second metal electrode (325) adjacent to the second metal chalcogenide layer (320), wherein the second metal chalcogenide layer (320) comprises the same metal as the second metal electrode (325).

2. The method of claim 1, further comprising:

the first metal chalcogenide layer and the second metal chalcogenide layer are formed using chemical vapor deposition.

3. The method of claim 2, further comprising:

in a chemical vapor deposition chamber, a first metal powder and a first chalcogen powder are disposed upstream of a substrate.

4. The method of claim 3, wherein the forming of the first metal chalcogenide layer comprises:

the first metal chalcogenide layer is epitaxially grown from an edge of the first metal electrode onto a substrate.

5. The method of claim 4, further comprising:

disposing a second metal powder and a second chalcogen powder upstream of the substrate in the chemical vapor deposition chamber,

wherein the forming of the second metal chalcogenide layer includes epitaxially growing the second metal chalcogenide layer from an edge of the first metal chalcogenide layer.

6. The method of claim 1, wherein said first metal chalcogenide layer and said second metal chalcogenide layer are formed without etching said first metal chalcogenide layer.

7. The method of claim 1, wherein the first metal chalcogenide layer or the second metal chalcogenide layer is formed from:

a metal selected from the group consisting of: tungsten oxide, tungsten trioxide, tungsten tetrachloride oxide, tungsten hexacarbonyl, molybdenum oxide, molybdenum trioxide, molybdenum chloride, molybdenum hexacarbonyl, bismuth telluride, bismuth selenide, bismuth oxide selenide, indium selenide, and gallium selenide; and

a chalcogen selected from the group consisting of: selenium, hydrogen selenide, sulfur, hydrogen sulfide, dimethyl selenium, dimethyl diselenide, dimethyl sulfide, and dimethyl disulfide.

8. The method of claim 1, wherein the semiconductor device is a diode.

9. A diode, comprising:

a substrate;

a first electrode disposed on the substrate and including a first metal;

a second electrode disposed on the substrate and including a second metal;

a lateral semiconductor heterojunction on the substrate between the first electrode and the second electrode, wherein the lateral semiconductor heterojunction comprises a first layer and a second layer arranged laterally, and wherein the first layer comprises a first metal and the second layer comprises a second metal,

wherein a portion of the first layer covers a portion of a top surface of the first electrode.

10. The diode of claim 9, wherein the first electrode directly abuts the substrate without any intervening material of the first or second layer.

11. The diode of claim 9, wherein at least a portion of the first metal in the first layer comprises the first metal from the first electrode.

12. The diode of claim 9, wherein the heterojunction comprises an atomically abrupt interface between the first layer and the second layer.

13. The diode of claim 9, wherein the first layer and the second layer are metal chalcogenide layers.

14. The diode of claim 13, wherein the first metal chalcogenide layer or the second metal chalcogenide layer is formed from:

a metal selected from the group consisting of: tungsten oxide, tungsten trioxide, tungsten tetrachloride oxide, tungsten hexacarbonyl, molybdenum oxide, molybdenum trioxide, molybdenum chloride, molybdenum hexacarbonyl, bismuth telluride, bismuth selenide, bismuth oxide selenide, indium selenide, and gallium selenide; and

a chalcogen selected from the group consisting of: selenium, hydrogen selenide, sulfur, hydrogen sulfide, dimethyl selenium, dimethyl diselenide, dimethyl sulfide, and dimethyl disulfide.

15. A method for forming a semiconductor device having a lateral semiconductor heterojunction, the method comprising:

disposing (610) a first metal powder (702A) and a first chalcogen powder (704A) upstream of a substrate (715) in a chemical vapor deposition chamber (750), wherein the substrate (715) has a first metal electrode (710), and wherein the first metal electrode (710) and the first metal powder (702A) comprise the same metal;

heating (615) a chemical vapor deposition chamber (750) while supplying a carrier gas (755) into the chemical vapor deposition chamber (750) to grow a first metal chalcogenide layer (705) that follows the geometry of the first metal electrode (710), wherein the first metal chalcogenide layer (705) comprises metal from the first metal electrode (710) and from the first metal powder (702A);

disposing (620) a second metal powder (702B) and a second chalcogen powder (704B) upstream of a substrate (715) in a chemical vapor deposition chamber (750); and

while supplying a carrier gas (755) into the chemical vapor deposition chamber (750), heating (625) the chemical vapor deposition chamber (750) to grow a second metal chalcogenide layer (720) that follows the geometry of the first metal chalcogenide layer (705) to form a lateral semiconductor heterojunction.

16. The method of claim 15, further comprising:

after growing the first metal chalcogenide layer and the second metal chalcogenide layer on a substrate, a second metal electrode is formed on the substrate.

17. The method of claim 16, wherein the first metal electrode and the first metal powder comprise a first transition metal and the second metal powder comprises a second transition metal.

18. The method of claim 16, further comprising:

depositing a metal on a substrate; and

patterning the deposited metal to form a geometry of the first metal electrode.

19. The method of claim 16, wherein the first metal chalcogenide layer or the second metal chalcogenide layer is formed from:

a metal selected from the group consisting of: tungsten oxide, tungsten trioxide, tungsten tetrachloride oxide, tungsten hexacarbonyl, molybdenum oxide, molybdenum trioxide, molybdenum chloride, molybdenum hexacarbonyl, bismuth telluride, bismuth selenide, bismuth oxide selenide, indium selenide, and gallium selenide; and

a chalcogen selected from the group consisting of: selenium, hydrogen selenide, sulfur, hydrogen sulfide, dimethyl selenium, dimethyl diselenide, dimethyl sulfide, and dimethyl disulfide.

20. The method of claim 15, wherein the semiconductor device is a diode.

Technical Field

Embodiments of the disclosed subject matter generally relate to a method for forming a semiconductor device having a lateral semiconductor heterojunction, a diode including a lateral semiconductor heterojunction, and a method of forming a semiconductor device.

Background

Two-dimensional (2D) Transition Metal Dichalcogenide (TMD) layered materials such as those with a molybdenum disulfide (MoS2) layer have been identified as high-switching-ratio (on-off ratio) semiconductors with broad prospects for high quantum yield optoelectronic devices, next-generation transistors, and integrated circuit applications. One problem with conventional transition metal dichalcogenide growth techniques is that there is little control over the growth site. For example, referring now to FIG. 1, in one conventional technique, sulfur (S)102 and transition metal 104 powders are disposed in a chemical vapor deposition chamber 106. Gas 108 is supplied to the CVD chamber 106, which causes the sulfur 102 and transition metal 104 powders to flow to the substrate 110, where the CVD chamber is heated106, a transition metal dichalcogenide layer 112 is grown on the substrate. Specifically, in the example shown, the transition metal is molybdenum (Mo), which is oxidized to form molybdenum trioxide (MoO)₃) Then combined with sulfur to form molybdenum disulfide (MoS)₂) Layer 112.

Although this conventional technique results in the formation of the transition metal dichalcogenide layer 112 on the substrate 110, there is little control over the location of the layer 112 growth on the substrate. This can be problematic for the formation of a p-n junction between two different transition metal dichalcogenide monolayers. Devices having a p-n junction between two different transition metal dichalcogenide monolayers are desirable because the p-n junction provides functions including current rectification, light emission, and photon collection.

One technique for achieving position-selective growth to form lateral heterojunctions involves a combination of chemical vapor deposition and photolithography. Specifically, a first layer is grown on a substrate using chemical vapor deposition, and then the substrate is removed from the chemical vapor deposition chamber to pattern the first layer using photolithography and reactive ion etching. The substrate is then placed in a chemical vapor deposition chamber to grow a second layer. Then, a first metal electrode and a second metal electrode are formed on the substrate.

Patterning by photolithography and reactive ion etching reduces the quality of the material in the first layer and results in a poor interface between the two layers, whereas an atomically abrupt interface between the two lateral layers of the heterojunction has been shown to be beneficial for the performance of the resulting semiconductor device with a lateral heterojunction. Furthermore, photolithography and reactive ion etching require the use of a photoresist, which results in the inevitable residues remaining on the substrate when growing the second layer. These residues act as growth seeds when the second layer is grown, which initiates uncontrolled growth.

It is therefore desirable to provide for the formation of lateral heterojunctions in a position-selective manner that provides an atomically sharp interface between two lateral layers.

Disclosure of Invention

According to an embodiment, there is a method for forming a semiconductor device having a lateral semiconductor heterojunction. A first metal chalcogenide layer of a lateral semiconductor heterojunction is formed on the substrate adjacent to the first metal electrode. The first metal chalcogenide layers include the same metal as the first metal electrodes, and at least some of the first metal chalcogenide layers include metal from the first metal electrodes. A second metal chalcogenide layer forming a lateral semiconductor heterojunction adjacent to the first metal chalcogenide layer. A second metal electrode is formed adjacent to the second metal chalcogenide layer. The second metal chalcogenide layer includes the same metal as the second metal electrode.

According to another embodiment, there is a diode comprising a substrate, a first electrode disposed on the substrate and comprising a first metal, a second electrode disposed on the substrate and comprising a second metal, and a lateral semiconductor heterojunction on the substrate between the first electrode and the second electrode. The lateral semiconductor heterojunction includes a first layer and a second layer arranged laterally, and the first layer includes a first metal and the second layer includes a second metal. A portion of the first layer covers a portion of a top surface of the first electrode.

According to yet another embodiment, there is a method for forming a semiconductor device having a lateral semiconductor heterojunction. In a chemical vapor deposition chamber, a first metal powder and a first chalcogen powder are disposed upstream of a substrate. The substrate has a first metal electrode, and the first metal electrode and the first metal powder include the same metal. While supplying the carrier gas into the chemical vapor deposition chamber, the chemical vapor deposition chamber is heated to grow the first metal chalcogenide layer following the geometry of the first metal electrode. The first metal chalcogenide layer includes metal from the first metal electrode and from the first metal powder. In the chemical vapor deposition chamber, a second metal powder and a second chalcogen powder are disposed upstream of the substrate. While supplying the carrier gas into the chemical vapor deposition chamber, the chemical vapor deposition chamber is heated to grow a second metal chalcogenide layer that follows the geometry of the first metal chalcogenide layer to form a lateral semiconductor heterojunction.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:

FIG. 1 is a schematic illustration of a conventional process for growing a transition metal dichalcogenide layer;

figure 2 is a flow diagram of a method of forming a lateral semiconductor heterojunction, according to an embodiment.

Figures 3a1-3C2 are schematic illustrations of a method of forming a lateral semiconductor heterojunction, according to an embodiment.

Figure 4 is a plot of a raman spectrum taken along a lateral semiconductor heterojunction formed in accordance with an embodiment.

Fig. 5A and 5B are intensity maps of raman spectra for a tungsten diselenide layer and a molybdenum disulfide layer, respectively, according to an embodiment.

Fig. 5C and 5D are intensity maps of photoluminescence spectra for a tungsten diselenide layer and a molybdenum disulfide layer, respectively, according to an embodiment.

Figure 6 is a flow diagram of a method of forming a lateral semiconductor heterojunction according to an embodiment; and

figures 7A-7E are schematic illustrations of a method of forming a lateral semiconductor heterojunction, according to an embodiment.

Detailed Description

The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Rather, the scope of the invention is defined by the appended claims. For simplicity, the following embodiments are discussed with respect to the terminology and structure of the metal chalcogenide layer growth technique.

Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

A method of forming a lateral semiconductor heterojunction, which in the illustrated embodiment is a diode, will now be described in connection with fig. 2 and 3a1-3C 2. Initially, a first metal chalcogenide layer 305 of a lateral semiconductor heterojunction is formed on a substrate 315 adjacent to a first metal electrode 310 (step 205 and fig. 3a1 and 3a 2). The first metal chalcogenide layer 305 includes the same metal as the first metal electrode 310, and at least some of the first metal chalcogenide layer 305 includes the metal from the first electrode 310. Next, a second metal chalcogenide layer 320 of a lateral semiconductor heterojunction is formed adjacent to the first metal chalcogenide layer 305 (step 210 and fig. 3B1 and 3B 2). Finally, a second metal electrode 325 is formed adjacent to the second metal chalcogenide layer 320 (step 215 and fig. 3C1 and 3C 2). The second metal chalcogenide layer 320 includes the same metal as the second metal electrode 325.

The inventors have recognized that by using the same metal for the first metal electrode 310 and the first metal chalcogenide layer 305, the first metal chalcogenide layer 305 is caused to follow the geometry of the first metal electrode 310 because the first metal electrode 310 acts as a catalyst to promote the growth of the first metal chalcogenide layer 305. This advantageously provides for the site-selective growth of the first metal chalcogenide layer 305. This also results in at least a portion of the first metal chalcogenide layer 305 covering the top surface of the first metal electrode 310, as shown in fig. 3a1-3C 2. The top surface overlying first metal electrode 310 does not affect device function because the underlying first metal electrode will have sufficient thickness to ensure transport through the portion of first metal chalcogenide layer 305 overlying first metal electrode 310.

Furthermore, as shown in fig. 3B1, 3B2, 3C1, and 3C2, the second metal chalcogenide layer 320 is epitaxially formed from the edge of the first metal chalcogenide layer 305, which provides an atomically abrupt interface between the first metal chalcogenide layer 305 and the second metal chalcogenide layer 320 that provides better performance of a device having a heterojunction as compared to conventional techniques that use photolithography to form a heterojunction.

The atomically abrupt interface of the heterojunction is confirmed by raman spectroscopic measurements of lateral semiconductor heterojunctions formed in the manner disclosed herein. In particular, FIG. 4 shows Raman spectroscopy measurements of a lateral semiconductor heterojunction with tungsten diselenide (WSe) in one of the layers₂) The other layer is molybdenum disulfide (MoS)₂). In the region with only tungsten diselenide (i.e., the lowest plot in fig. 4) or only molybdenum disulfide (i.e., the highest plot in fig. 4), at about 250cm^-1(A_1gMode), 405cm^-1(A_1gMode) and 385cm^-1(E_2gPattern) a characteristic peak is found. In addition, the interface between the tungsten diselenide layer and the molybdenum disulfide layer (i.e., the middle dotted line of fig. 4) shows molybdenum disulfide and tungsten diselenide coexisting without the formation of an alloy. Thus, there is no intermediate material, such as an alloy, between the tungsten diselenide layer and the molybdenum disulfide layer.

The atomically abrupt interface of the heterojunction is also confirmed by raman spectroscopy and photoluminescence intensity mapping of a lateral semiconductor heterojunction formed in the manner disclosed herein, wherein one layer is tungsten diselenide and the other layer is molybdenum disulfide. Specifically, according to an embodiment, fig. 5A and 5B are intensity maps of raman spectra for the tungsten diselenide and molybdenum disulfide layers, respectively, and fig. 5C and 5D are intensity maps of photoluminescence spectra for the tungsten diselenide and molybdenum disulfide layers, respectively. Fig. 5A-5D each show a tungsten electrode 510, a tungsten diselenide layer 505, and a molybdenum disulfide layer 520. As shown in fig. 5A and 5C, the growth of the tungsten diselenide layer 505 follows the geometry of the tungsten electrode 510 and exhibits high selectivity in terms of growth position compared to the sapphire base surface of the substrate (not shown). Furthermore, as shown in fig. 5A-5D, tungsten diselenide layer 505 and molybdenum disulfide layer 520 are well separated without alloying at the lateral junction of the two layers.

A method of forming a semiconductor device having a lateral heterojunction using chemical vapor deposition will now be described in connection with figures 6 and 7A-7E. Embodiments of the method will be described in connection with the formation of a tungsten diselenide-molybdenum disulfide heterojunction device. However, heterojunctions using other metals and chalcogens disclosed herein can be formed using this method.

Initially, a first metal electrode 710 is formed on a substrate 715 (step 605 and fig. 7A). In this embodiment, a first metal electrode 710 is formed outside the chemical vapor deposition chamber by forming a 50nm thick tungsten electrode on a sapphire substrate, for example, by physical vapor sputtering, followed by photolithographic patterning. The substrate 715, including the first metal electrode 710, may then be cleaned, for example, using acetone and sonication for five minutes, to clean the surface and increase growth options. The first metal electrode 710 can be formed in any desired geometry, which can be regular (i.e., corresponding to a geometric shape) or irregular (i.e., not corresponding to a geometric shape). The ability to select the geometry of the first metal electrode 710.

In the chemical vapor deposition chamber 730, a first metal powder 702A and a first chalcogen powder 704A are disposed upstream of a substrate 715 (step 610 and fig. 7B). In this embodiment, first metal powder 702A is tungsten trioxide powder and first chalcogen powder 704A is selenium. The chemical vapor deposition chamber 730 can be maintained at a temperature of, for example, 250 ℃ while the powders 702A and 704A are placed in the chemical vapor deposition chamber 730.

While supplying the carrier gas into the chemical vapor deposition chamber 730, the chemical vapor deposition chamber 730 is heated to grow the first metal chalcogenide layer 705 following the geometry of the first electrode 710 (step 615 and fig. 7C). In this example, argon/hydrogen (Ar/H) is used₂) The chemical vapor deposition chamber 730 can be heated to, for example, 850 ℃ for 15 minutes with a carrier gas (65sccm/5sccm) supplied to the chemical vapor deposition chamber 730, the argon/hydrogen carrier gas being maintained at a pressure of 20 Torr. The growth of tungsten diselenide layer 705 follows the geometry of first metal electrode 710 by selenization on the tungsten metal surface of first metal electrode 710 and by epitaxial growth from the tungsten metal edge of first metal electrode 710 onto the basal plane of sapphire substrate 715. Thus, the disclosed method provides for the positionally selective growth of the first layer. In addition, the chemical vapor deposition process causes tungsten diselenide layer 705 to include tungsten from the first goldSome of the metal electrode 710.

In the chemical vapor deposition chamber 730, the second metal powder 702B and the second chalcogen powder 704B are disposed upstream of the substrate 715 (step 620 and fig. 7D). In this embodiment, the second metal powder 702B is molybdenum trioxide, and the second chalcogen powder 704B is sulfur. This can be performed in the same chemical vapor deposition chamber as the previous step or in a different chemical vapor deposition chamber. The use of a different chemical vapor deposition chamber is advantageous because after the tungsten diselenide layer 705 is grown, there will be some residue or by-product covering the chamber. However, the same chemical vapor deposition chamber can be used as long as these residues or byproducts are removed from the chemical vapor deposition chamber used to grow tungsten diselenide layer 705.

While supplying the carrier gas into the chemical vapor deposition chamber 730, the chemical vapor deposition chamber 730 is heated to grow the second metal chalcogenide layer 720 following the geometry of the first metal chalcogenide layer (step 625 and fig. 7D). In this embodiment, the chemical vapor deposition chamber 730 can be heated to, for example, 750 ℃ for 10 minutes while supplying an argon carrier gas (60sccm) to the chemical vapor deposition chamber 730, the argon carrier gas being maintained at a pressure of 50 Torr. The molybdenum disulfide layer grows epitaxially from the edge of the tungsten diselenide layer, follows the geometry of the tungsten diselenide layer, and forms an atomically abrupt interface between the two layers. In contrast, conventional layer heterojunctions are typically formed using etching that does not provide an atomically abrupt interface between layers, thus resulting in reduced device performance as compared to layer heterojunctions formed in the disclosed manner. In other words, an atomically abrupt interface can be achieved by forming a heterojunction without etching the first metal chalcogenide layer.

Finally, a second electrode 725 is then formed on the substrate 725 (step 630 and fig. 7E). In this embodiment, a 5nm/25nm thick molybdenum/nickel electrode is formed on sapphire substrate 715, for example by physical vapor sputtering, followed by photolithographic patterning, while a second metal electrode 725 is formed outside of chemical vapor deposition chamber 730.

Thus, as can be appreciated from the above discussion, the first metal chalcogenide layer 705 and the first electrode 710 comprise the same metal (tungsten in this example), and the second metal chalcogenide layer 720 and the second electrode 725 comprise the same metal (molybdenum in this example).

Although embodiments have been described in which tungsten trioxide and molybdenum trioxide are used as precursor (precursor) metals and selenium and sulfur are used as chalcogen precursors to form heterojunctions, other metals and chalcogen precursors can be used. For example, the metal precursor can be tungsten oxide (WO)₂) Tungsten tetrachlorooxide (WOCl)₄) Tungsten hexacarbonyl ((W (CO))₆) Molybdenum oxide (MoO)₂) Molybdenum chloride (MoCl)₅) Molybdenum hexacarbonyl ((Mo (CO))₆) Bismuth telluride (Bi)₂Te₃) Bismuth selenide (Bi)₂Se₃) Bismuth oxide selenide (Bi)₂O₂Se), indium selenide (InSe) or gallium selenide (GaSe). In addition, the chalcogen can be hydrogen selenide (H)₂Se), hydrogen sulfide (H)₂S), dimethylselenium (DMSe), dimethyldiselenide (DMDSe), Dimethylsulfide (DMS), or dimethyldisulfide (DMDS).

The disclosed embodiments provide a method for forming a semiconductor device having a lateral semiconductor heterojunction, a diode comprising a lateral semiconductor heterojunction, and a method of forming a semiconductor device. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a thorough understanding of the claimed invention. However, it will be understood by those skilled in the art that the various embodiments may be practiced without such specific details.

Although the features and elements of the exemplary embodiments of the present invention are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.

This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims.