TW201917895A - Semiconductor device - Google Patents

Abstract

A semiconductor device is provided. The semiconductor device includes a source, a drain, a composite channel structure and a gate structure. The source has a first conductive type. The drain has a second conductive type. The composite channel structure is located between the source and the drain along a first direction. The composite channel structure includes a first channel structure and a second channel structure. The first channel structure is located between the source and the second channel structure, and has a first bandgap. The second channel structure is located between the first channel structure and the drain, and has a second bandgap. The first bandgap is less than the second bandgap. The gate structure is abutted with the composite channel structure along a second direction. The first direction is intersected with the second direction.

Description

Semiconductor component

This invention relates to a semiconductor component and, more particularly, to a field effect transistor.

With the development of integrated circuits, the feature size of semiconductor components is continuously shortened. For field effect transistors, shortening the feature size can cause problems such as an increase in subthreshold swing. In this regard, it is difficult to effectively reduce the sub-threshold swing by controlling the field effect transistor of the switch with a drift-diffusion mechanism.

In contrast, a tunneling FET that controls the switch with a band to band tunneling mechanism can further reduce the sub-threshold swing. However, for current through-type field effect transistors, it is difficult to reduce the leakage current without affecting the on current.

The present invention provides a semiconductor element capable of reducing leakage current without substantially affecting an on current.

The semiconductor device of the present invention includes a source, a drain, a composite channel structure, and a gate structure. The source has a first conductivity type. The drain has a second conductivity type. The composite channel structure is located between the source and the drain in a first direction. The composite channel structure includes a first channel structure and a second channel structure. The first channel structure is between the source and the second channel structure and has a first energy gap. The second channel structure is located between the first channel structure and the drain and has a second energy gap. The first energy gap is smaller than the second energy gap. The gate structure is adjacent to the composite channel structure in the second direction. The first direction is interleaved with the second direction.

In an embodiment of the invention, the first energy gap is smaller than the energy gap of the source.

In an embodiment of the invention, the first energy gap is equal to the energy gap of the source.

In an embodiment of the invention, the first channel structure has a first conduction band and a first valence band, and the second channel structure has a second conduction band and a second valence band. The first conduction band is lower than the second conduction band, and the first valence band is lower, higher or flush with the second valence band; or the first conduction band is flush with the second conduction band, and the first valence band is lower than Or higher than the second price band.

In an embodiment of the invention, the gate structure includes a first gate structure and a second gate structure. The first gate structure and the second gate structure are respectively adjacent to opposite sides of the composite channel structure in the second direction.

In an embodiment of the invention, the first gate structure includes a first gate dielectric layer and a first gate. The first gate dielectric layer is between the first gate and the composite channel structure. The second gate structure includes a second gate dielectric layer and a second gate. The second gate dielectric layer is between the second gate and the composite channel structure.

In an embodiment of the invention, the semiconductor device further includes a source contact layer and a drain contact layer. The source contact layer is connected to the source and the drain contact layer is connected to the drain.

In an embodiment of the invention, the material of the source, drain and composite channel structures comprises a Group IV semiconductor, a III-V compound semiconductor, a II-VI compound semiconductor, or a combination thereof.

In an embodiment of the invention, the elemental species of the material of the first channel structure is different from the elemental species of the material of the second channel structure.

In an embodiment of the invention, the material of the first channel structure and the material of the second channel structure comprise the same element type, and the element ratios are different from each other.

Based on the above, the semiconductor element of the embodiment of the present invention includes a composite channel structure. The composite channel structure includes a first channel structure of low energy gap and a second channel structure of high energy gap. As such, in the closed state of the semiconductor component, the high-gap second channel structure can form an energy barrier to block leakage current from the source to the composite channel structure. In addition, in the off state of the semiconductor, electrons in the valence band of the source are less likely to cross the potential well formed by the first channel structure, so that it is difficult to move from the source to the drain via the composite channel structure. On the other hand, in the on state of the semiconductor element, the energy barrier formed by the second channel structure of the high energy gap is reduced without substantially affecting the on current. In this way, the leakage current of the semiconductor element can be suppressed without substantially affecting the on current.

The above described features and advantages of the invention will be apparent from the following description.

1 is a schematic illustration of a semiconductor component in accordance with some embodiments of the present invention.

Referring to FIG. 1, a semiconductor device 100 of an embodiment of the present invention is a tunneling field effect transistor (tunneling FET). The semiconductor device 100 includes a source 102, a drain 104, a composite channel structure 106, and a gate structure 108. In some embodiments, the source 102, the drain 104, and the composite channel structure 106 may each be an epitaxial layer, but the present invention is not limited to the method of manufacturing the semiconductor device 100.

The source 102 and the drain 104 are arranged in the first direction D1. The material of the source 102 and the drain 104 may include a Group IV semiconductor, a III-V compound semiconductor, a II-VI compound semiconductor, or a combination thereof. For example, the materials of the source 102 and the drain 104 may include tantalum, niobium, tantalum carbide, tantalum telluride, gallium arsenide, aluminum arsenide, indium arsenide, indium gallium arsenide, aluminum gallium arsenide, phosphating. Indium, indium gallium phosphide, gallium nitride, aluminum nitride, indium gallium nitride, aluminum gallium nitride, gallium antimonide, aluminum telluride, indium antimonide, antimony gallium arsenide, zinc oxide, zinc sulfide, magnesium oxide Zinc or a combination thereof. In the embodiment shown in FIG. 1, the material of the source 102 is different from the material of the drain 104. For example, the material of the source 102 may be gallium germanium arsenide, and the material of the drain 104 may be indium gallium arsenide. In other embodiments, the material of the source 102 may be the same as the material of the drain 104, such as indium gallium arsenide. In addition, those skilled in the art can adjust the proportion of each element in the compound semiconductor according to the design requirements, and the invention is not limited thereto.

The source 102 can be doped to have a first conductivity type, and the drain 104 can be doped to have a second conductivity type. In some embodiments, the first conductivity type is a P type and the second conductivity type is an N type. As such, the semiconductor component 100 can be an N-type via-type field effect transistor. In other embodiments, the first conductivity type can be N-type and the second conductivity type can be P-type. In other words, the semiconductor device 100 can also be a P-type via-type field effect transistor. The P-type dopant may include carbon or magnesium, cerium, zinc, or a combination thereof, and the N-type dopant may include cerium, tin, antimony, or a combination thereof. In some embodiments, the source 102 has a doping concentration ranging from 10 ¹⁸ to 10 ²¹ cm ^-3 . The doping concentration of the drain 104 ranges from 10 ¹⁸ to 10 ²¹ cm ^-3 .

The composite channel structure 106 is located between the source 102 and the drain 104. The source 102, the composite channel structure 106, and the drain 104 are arranged along the first direction D1. The composite channel structure 106 includes a first channel structure 106a and a second channel structure 106b. The first channel structure 106a is between the source 102 and the second channel structure 106b, and the second channel structure 106b is located between the first channel structure 106a and the drain 104. The first channel structure 106a has a first energy gap and the second channel structure 106b has a second energy gap. The first energy gap is smaller than the second energy gap.

The first channel structure 106a has a first conduction band and a first valence band, and the second channel structure 106b has a second conduction band and a second valence band. In some embodiments, the first conduction band is lower than the second conduction band and the first valence band is higher than the second valence band. In some embodiments, the first conduction band is lower than the second conduction band and the first valence band is flush with the second valence band. In some embodiments, the first conduction band is flush with the second conduction band and the first valence band is higher than the second valence band. In some embodiments, the first conduction band is lower than the second conduction band and the first valence band is lower than the second valence band. In some embodiments, the first conductive strip is flush with the second conductive strip and the first valence band is lower than the second valence band.

The material of the first channel structure 106a and the material of the second channel structure 106b may include a Group IV semiconductor, a III-V compound semiconductor, a II-VI compound semiconductor, or a combination thereof. In some embodiments, the material of the first channel structure 106a is different than the material of the second channel structure 106b. For example, the material of the first channel structure 106a may be indium gallium arsenide or indium phosphide. The material of the second channel structure 106b may be gallium arsenide or indium gallium phosphide. In other embodiments, the first channel structure 106a is the same material as the second channel structure 106b, but differs in composition ratio. For example, the first channel structure 106a and the second channel structure 106b are both indium gallium arsenide, gallium arsenide or gallium arsenide. The first energy gap of the first channel structure 106a can be made smaller than the second energy gap of the second channel structure 106b by adjusting the ratio of elements in the above compound.

In some embodiments, the first energy gap of the first channel structure 106b is smaller than the second energy gap of the second channel structure 106b, and the first energy gap is smaller than the energy gap of the source 102. For example, in the embodiment illustrated in FIG. 1, the elemental species of material of the first channel structure 106a is different from the elemental species of material of the second channel structure 106b. For example, the material of the first channel structure 106a includes indium gallium arsenide, and the material of the second channel structure 106b includes gallium arsenide. As such, the first channel structure 106a can have a first energy gap and the second channel structure 106b can have a second energy gap, and the first energy gap is smaller than the second energy gap. Therefore, a heterojunction can be formed between the source 102 and the first channel structure 106b, and an effective tunneling barrier for electrons to pass through the source 102 to the first channel structure 106a can be reduced. ). Therefore, the on current of the semiconductor element 100 can be improved.

In some embodiments, the composite channel structure 106 can be undoped, but an intrinsic layer. In other embodiments, the composite channel structure 106 can also be doped to have a first conductivity type or a second conductivity type. The doping concentration of the composite channel structure 106 can be lower than the doping concentration of the source 102 and the drain 104. For example, the doping concentration of the composite channel structure 106 can range from 10 ¹⁴ to 10 ¹⁷ cm ^-3 .

The first channel structure 106a has a first length L1 in the first direction D1 and the second channel structure 106b has a second length L2 in the first direction D1. In some embodiments, the ratio (L1/L2) of the first length L1 to the second length L2 is greater than zero and less than or equal to 14. In some embodiments, the ratio (L1/L2) of the first length L1 to the second length L2 may be 0.07 to 6.50. In other embodiments, the ratio of the first length L1 to the second length L2 (L1/L2) may also be 0.07 to 4. However, those skilled in the art can adjust the first length and the second length respectively according to the characteristics of the components, and the invention is not limited thereto.

The semiconductor component 100 further includes a gate structure 108. Gate structure 108 is adjacent to composite channel structure 106 in a second direction D2. The second direction D2 is staggered in the first direction D1. In some embodiments, the second direction D2 is perpendicular to the first direction D1. In some embodiments, the gate structure 108 includes a first gate structure 108a and a second gate structure 108b. The first gate structure 108a and the second gate structure 108b are adjacent to opposite sides of the composite channel structure 106 in the second direction D2. Similarly, the gate dielectric layer 110 can include a first gate dielectric layer 110a and a second gate dielectric layer 110b, and the gate 112 can include a first gate 112a and a second gate 112b. The first gate dielectric layer 110a is between the first gate 112a and the composite channel structure 106, and the second gate dielectric layer 110b is between the second gate 112b and the composite channel structure 106. The materials of the first gate dielectric layer 110a and the second gate dielectric layer 110b may include tantalum oxide, tantalum nitride, aluminum oxide, tantalum oxide, or a combination thereof, respectively. The materials of the first gate 112a and the second gate 112b may respectively include platinum, titanium, aluminum, gold, gallium, lead, antimony, cadmium, indium or a combination thereof. Those skilled in the art can select appropriate gate dielectric material and gate material according to the characteristics of the device, and the invention is not limited thereto. In some embodiments, the material of the first gate dielectric layer 110a may be the same as or different from the material of the second gate dielectric layer 110b. Similarly, the material of the first gate 112a may be the same as or different from the material of the second gate 112b. In some embodiments, the gate structure 108 can also be a single gate structure, or include more than three gate structures, and the present invention is not limited to the number of gate structures.

In some embodiments, the semiconductor device 100 further includes a source contact layer 114 and a gate contact layer 116. The source contact layer 114 is connected to the source 102, and the drain contact layer 116 is connected to the drain 104. In some embodiments, the source contact layer 114 is disposed on a side of the source 102 relative to the composite channel structure 106 and the gate contact layer 116 is disposed on a side of the drain 104 opposite the composite channel structure 106. The material of the source contact layer 114 and the material of the gate contact layer 116 may each comprise a metal or a metal compound. For example, the material of the source contact layer 114 and the material of the gate contact layer 116 may respectively include platinum, titanium, aluminum, gold, gallium, lead, antimony, cadmium, indium or a combination thereof, and the present invention does not limit. By providing the source contact layer 114 and the drain contact layer 116, the contact resistance of the source 102 and the contact resistance of the drain 104 can be reduced, respectively.

FIG. 2A is a band diagram of the semiconductor device 100 of FIG. 1 in an on state. FIG. 2B is an energy band diagram of the semiconductor device 100 of FIG. 1 in a closed state. In FIGS. 2A and 2B, the semiconductor device 100 is an N-type field-effect transistor. The energy band includes a conduction band CB (conduction band) and a valence band VB (valence band). The region A is the energy band of the source 102, the region B1 is the energy band of the first channel structure 106a, the region B2 is the energy band of the second conduction structure 106b, and the region C is the energy band of the drain 104. Referring to FIG. 2A and FIG. 2B, since the composite channel structure 106 is composed of a low energy gap first channel structure 106a and a high energy gap second channel structure 106b, the conduction band CB and the valence band VB form a potential energy well in the region B1 ( Potential well) and forming a potential barrier in region B2.

Referring to FIG. 1 and FIG. 2A, when the gate structure 108 has a positive bias voltage greater than a threshold voltage for the source 102 and the gate 104 has a positive bias voltage with respect to the source 102, the semiconductor device 100 is turned on. (on-state). As indicated by the arrows in Figure 2A, electrons in the valence band of source 102 can be tunneled to first channel structure 106a in a band to band tunneling manner. In the on state, the energy band of the composite channel structure 106 (region B1 and region B2) is reduced. Thus, electrons that pass through the first channel structure 106a can cross the energy barrier of the conduction band CB in region B1 and move to the drain 104 to form an on current.

Referring to FIGS. 1 and 2B, when the bias voltage of the gate structure 108 with respect to the source 102 is less than the initial voltage, the semiconductor device 100 is in an off state. In the off state, electrons in the valence band of source 102 can still pass through to first channel structure 106a. However, in the off state, the energy band of the composite channel structure 106 (area B1 and region B2) is not reduced. Therefore, as shown by the leakage path LC1 of FIG. 2B, electrons that pass through the first channel structure 106a are difficult to move to the drain 104 across the energy barrier of the conduction band CB in the region B2, so that leakage current can be reduced. On the other hand, as shown by the leakage path LC2 of FIG. 2B, the electrons in the valence band of the source 102 need to cross the potential well of the valence band VB in the region B1, so that the gate structure 108 is negative to the source 102. When biased, it moves to the drain 104 in a twisting manner. In other words, the situation of the ambipolar conduction of the semiconductor element 100 can be reduced.

3 is a schematic diagram of a semiconductor device 300 in accordance with further embodiments of the present invention.

Referring to FIGS. 1 and 3, the semiconductor device 300 shown in FIG. 3 is similar to the semiconductor device 100 shown in FIG. The difference between the two is that the energy gap of the source 302 of the semiconductor device 300 is equal to the first energy gap of the first channel structure 106a. In some embodiments, the material of the source 302 can be the same as the material of the first channel structure 106a and the drain 104, such as indium gallium arsenide. As such, the source 302 and the first channel structure 106a may be homojunctions.

Next, the effects of the examples of the present invention were verified by Experimental Example 1 to Experimental Example 13 and Comparative Examples 1 and 2.

Referring to FIG. 1, in Experimental Example 1-13, the semiconductor device 100 is an N-type via-type field effect transistor. The material of the source 102 and the second channel structure 106b is GaAs _0.51 Sb _0.49 . The source 102 is doped to a P type in which the dopant is carbon and the doping concentration is 5 ^{́10 19} cm ^-3 . The second channel structure 106b is an undoped intrinsic layer. The material of the first channel structure 106a and the drain 104 is In _0.53 Ga _0.47 As. The drain 104 is doped to be N-type, wherein the dopant is germanium and the doping concentration is 1 ́10 ¹⁹ cm ^-3 . The first channel structure 106a is an undoped intrinsic layer. In the first direction D1, the lengths of the source 102 and the drain 104 are 300 nm and 200 nm, respectively. The first gate dielectric layer 110a and the second gate dielectric layer 110b are both hafnium oxide and have a thickness of 5 nm. The material of the first gate 112a and the second gate 112b is platinum. The material of the source contact layer 114 and the gate contact layer 116 is a titanium-gold alloy.

Referring to Table 1 below, the total length of the composite channel structure 106 of Experimental Examples 1 to 13 in the first direction D1 (that is, the sum of the first length L1 and the second length L2) is 150 nm. The first lengths L1 of the experimental examples 1 to 13 are 130 nm, 120 nm, 110 nm, 100 nm, 90 nm, 80 nm, 70 nm, 60 nm, 50 nm, 40 nm, 30 nm, 20 nm, and 10 nm. In addition, the second lengths L2 of the experimental examples 1 to 13 are 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130, respectively. Nm and 140 nm.

On the other hand, the semiconductor elements of Comparative Examples 1 and 2 were similar to the semiconductor elements of Experimental Examples 1 to 13. The difference between Comparative Example 1 and Experimental Example 1-13 is that the channel structure of Comparative Example 1 is not the composite channel structure 106 shown in FIG. The channel structure of Comparative Example 1 includes only the first channel structure of the low energy gap, and does not include the second channel structure of the high energy gap. In addition, the difference between Comparative Example 2 and Comparative Example 1 is that the channel structure of Comparative Example 2 includes only the second channel structure of the high energy gap, and does not include the first channel structure of the low energy gap.

The results of simulation of the semiconductor elements of Experimental Example 1-13 and Comparative Examples 1 and 2 by the simulation software Silvaco Altas TCAD are shown in Table 1 below. The turn-off current, on-current, and average sub-threshold swing of Table 1 below are values measured at a fixed drain-to-source bias of 0.5 V and varying the bias of the gate structure to the source.

Table 1

It can be seen from the above Table 1 that the shutdown currents of Experimental Examples 1-13 are all smaller than the shutdown currents of Comparative Examples 1 and 2. On the other hand, the difference between the on-current of Experimental Example 1-13 and the on-current of Comparative Example 1 was small, and the on-current of Experimental Example 1-13 was larger than that of Comparative Example 2. From this, it is understood that the semiconductor element including the composite channel structure (Experimental Example 1-13) can effectively suppress the leakage current and does not substantially affect the on-current. In the case where the sum of the first length L1 and the second length L2 is 150 nm, the ratio (L1/L2) of the first length L1 to the second length L2 may range from 0.07 to 6.5. In this case, from the data of the average sub-threshold swing, it can be seen that the semiconductor element of the experimental example 2-13 in which the ratio (L1/L2) of the first length L1 to the second length L2 is in the range of 0.07 to 4 can be better. Switching characteristics. However, those having ordinary skill in the art can adjust the first length L1 and the second length L2 according to design requirements, and the present invention is not limited to the ratio range of the first length L1 and the second length L2.

In summary, based on the above, the semiconductor device of the embodiment of the present invention includes a composite channel structure. The composite channel structure includes a first channel structure of low energy gap and a second channel structure of high energy gap. As such, in the closed state of the semiconductor component, the high-gap second channel structure can form an energy barrier to block leakage current from the source to the composite channel structure. In addition, in the off state of the semiconductor, electrons in the valence band of the source are less likely to cross the potential well formed by the first channel structure, so that it is difficult to move from the source to the drain via the composite channel structure. On the other hand, in the on state of the semiconductor element, the energy barrier formed by the second channel structure of the high energy gap is reduced without substantially affecting the on current. In this way, the leakage current of the semiconductor element can be suppressed without substantially affecting the on current.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100, 300‧‧‧ semiconductor components

102, 302‧‧‧ source

104‧‧‧汲polar

106‧‧‧Composite channel structure

106a‧‧‧First channel structure

106b‧‧‧Second channel structure

108‧‧‧ gate structure

108a‧‧‧First gate structure

108b‧‧‧Second gate structure

110a‧‧‧First gate dielectric layer

110b‧‧‧second gate dielectric layer

112a‧‧‧first gate

112b‧‧‧second gate

114‧‧‧Source contact layer

116‧‧‧汲 contact layer

A, B1, B2, C‧‧‧ areas

CB‧‧‧Transmission belt

VB‧‧ ‧ price belt

D1‧‧‧ first direction

D2‧‧‧ second direction

L1‧‧‧ first length

L2‧‧‧ second length

LC1, LC2‧‧‧ leakage path

1 is a schematic illustration of a semiconductor component in accordance with some embodiments of the present invention. 2A is a band diagram of the semiconductor device of FIG. 1 in an on state. 2B is an energy band diagram of the semiconductor device of FIG. 1 in a closed state. 3 is a schematic diagram of a semiconductor device in accordance with further embodiments of the present invention.

Claims (10)

A semiconductor device comprising: a source having a first conductivity type; a drain having a second conductivity type; and a composite channel structure between the source and the drain in a first direction, wherein the composite The channel structure includes: a first channel structure between the source and the drain and having a first energy gap; and a second channel structure between the first channel structure and the drain And having a second energy gap, wherein the first energy gap is smaller than the second energy gap; and a gate structure adjacent to the composite channel structure in a second direction, wherein the first direction and the first The two directions are staggered. The semiconductor device of claim 1, wherein the first energy gap is smaller than an energy gap of the source. The semiconductor device of claim 1, wherein the first energy gap is equal to an energy gap of the source. The semiconductor device of claim 1, wherein the first channel structure has a first conduction band and a first valence band, and the second channel structure has a second conduction band and a second valence band, wherein The first conductive strip is lower than the second conductive strip, and the first valence band is lower, higher or flush with the second valence band; or wherein the first conductive strip is flush with The second conduction band is described, and the first valence band is higher or lower than the second valence band. The semiconductor device of claim 1, wherein the gate structure comprises a first gate structure and a second gate structure, and the first gate structure and the second gate structure are respectively The second direction is adjacent to opposite sides of the composite channel structure. The semiconductor device of claim 5, wherein the first gate structure comprises a first gate dielectric layer and a first gate, and the first gate dielectric layer is located at the first gate Between the composite channel structures, the second gate structure includes a second gate dielectric layer and a second gate, and the second gate dielectric layer is located in the second gate and the composite channel structure between. The semiconductor device of claim 1, further comprising a source contact layer and a drain contact layer, wherein the source contact layer is connected to the source, and the drain contact layer is connected to the Bungee jumping. The semiconductor device according to claim 1, wherein the source, the drain, and the material of the composite channel structure comprise a group IV semiconductor, a III-V compound semiconductor, a II-VI compound semiconductor or Its combination. The semiconductor element according to claim 8, wherein the element type of the material of the first channel structure is different from the element type of the material of the second channel structure. The semiconductor device according to claim 8, wherein the material of the first channel structure and the material of the second channel structure comprise the same element type, and the element ratios are different from each other.