Semiconductor device with fin and related methods

Abstract

A semiconductor device may include a substrate, a fin above the substrate and having a channel region therein, and source and drain regions adjacent the channel region to generate shear and normal strain on the channel region. A semiconductor device may include a substrate, a fin above the substrate and having a channel region therein, source and drain regions adjacent the channel region, and a gate over the channel region. The fin may be canted with respect to the source and drain regions to generate shear and normal strain on the channel region.

Claims

1. A device, comprising: a substrate; a plurality of fins on the substrate; source and drain regions adjacent to the plurality of fins, the source and drain regions have an extension, the plurality of fins are canted with respect to the source and drain regions and the extension of the source and drain regions; a channel region in each of the fins, the channel regions being between the source and drain region; and a gate structure over the channel regions, the gate structure has an extension that is substantially parallel to the extension of the source and drain regions.

2. The device of claim 1 wherein the channel region includes shear and normal strain in response to the plurality of fins being canted with respect to the source and drain regions.

3. The device of claim 1 wherein the plurality of fins are canted at a 45 degrees angle with respect to the source and drain regions.

4. The device of claim 1 wherein the plurality of fins are canted in the range of 22.5 and 67.5 degrees with respect to the source and drain regions.

5. The device of claim 1 wherein the plurality of fins are canted in the range of 40 and 50 degrees with respect to the source and drain regions.

6. The device of claim 1 further comprising a dielectric layer between the substrate and the plurality of fins.

7. The device of claim 1 wherein the source and drain regions each includes silicon germanium.

8. A device, comprising: a substrate; a plurality of gate structures on the substrate, each gate structure having a length that extends along a first axis; a plurality of fins extending from a surface of the substrate and aligned with each other along a second axis, each fin overlapped by a respective one of the plurality of gate structures, the first axis at an oblique angle to the second axis; and source and drain regions adjacent to the plurality of fins and between ones of the plurality of gate structures, the source and drain regions are aligned along the first axis.

9. The device of claim 8 wherein the plurality of gate structures are staggered with respect to each other.

10. The device of claim 8 further comprising a plurality of channel regions in the plurality of fins, each channel region being between the source and drain regions.

11. The device of claim 10 wherein the plurality of gate structures are above the plurality of channel regions.

12. The device of claim 10 wherein the plurality of channel regions include a strain in response to the oblique angle between the first and second axis.

13. The device of claim 8 wherein the plurality of gate structures are controlled by a single signal.

14. A device, comprising: a substrate; a plurality of fins aligned along a first axis; a gate structure aligned along a second axis that is oblique to the first axis, the gate structure positioned above the plurality of fins; and source and drain regions adjacent to the gate structure, the source and drain regions are aligned along the second axis.

15. The device of claim 14 further comprising a channel region positioned below the gate structure, the channel region being between the source and drain regions.

16. The device of claim 15 wherein the channel region includes shear and normal strain in response to the oblique angle between the first and second axis.

17. A device, comprising: a substrate; a plurality of fins on the substrate; source and drain regions adjacent to the plurality of fins, the plurality of fins are canted with respect to the source and drain regions; a channel region in each of the fins, the channel regions being between the source and drain region, the channel region includes shear and normal strain in response to the plurality of fins being canted with respect to the source and drain regions; and a gate structure over the channel regions.

18. The device of claim 17 wherein the plurality of fins are canted in the range of 40 and 50 degrees with respect to the source and drain regions.

19. The device of claim 17 wherein the gate structure has an extension that is substantially parallel to an extension of the source and drain regions where the extension of the source and drain regions is canted with respect to the plurality of fins.

20. A device, comprising: a substrate; a plurality of fins aligned along a first axis; a gate structure aligned along a second axis that is oblique to the first axis, the gate structure positioned above the plurality of fins, the gate structure has an extension that is aligned along the second axis; and source and drain regions adjacent to the gate structure, the source and drain regions have an extension that is substantially parallel to the extension of the gate structure.

21. The device of claim 20 wherein the source and drain regions are aligned along the second axis.

22. A device, comprising: a substrate; a plurality of fins on the substrate; source and drain regions adjacent to the plurality of fins, the plurality of fins are canted with respect to the source and drain regions; a channel region in each of the fins, the channel regions being between the source and drain region; and a gate structure over the channel regions, the gate structure aligned substantially parallel to the source and drain regions.

23. The device of claim 22 wherein the channel region includes shear and normal strain in response to the plurality of fins being canted with respect to the source and drain regions.

24. The device of claim 22 wherein the plurality of fins are canted in the range of 40 and 50 degrees with respect to the source and drain regions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a perspective view of a semiconductor device, according to the prior art.

(2) FIG. 2 is a diagram illustrating normal and shear stress, according to the present disclosure.

(3) FIG. 3A is a schematic diagram of a top plan view of a semiconductor device, according to the present disclosure.

(4) FIG. 3B is a schematic diagram of a top plan view of another embodiment of a semiconductor device, according to the present disclosure.

(5) FIGS. 4A-4C are schematic diagrams of a top plan view, a cross-sectional view along line B-B, and a cross-sectional view along line C-C of a step in making a plurality of semiconductor devices of FIG. 3A, according to the present disclosure.

(6) FIGS. 5A-5C are schematic diagrams of a top plan view, a cross-sectional view along line B-B, and a cross-sectional view along line C-C of a step in making a plurality of semiconductor devices of FIG. 3A, according to the present disclosure.

(7) FIGS. 6A-6B are schematic diagrams of a top plan view of semiconductor devices of FIGS. 3A and 3B, respectively, with stress indicator arrows.

(8) FIGS. 7A-7D are schematic diagrams of layer stacks for embodiments of a semiconductor device, according to the present disclosure.

(9) FIGS. 8A and 8B are schematic diagrams of a top plan view and an enlarged top plan view of another embodiment of a semiconductor device, according to the present disclosure.

(10) FIGS. 9A-9C are schematic diagrams of a top plan view, a cross-sectional view along line B-B, and a cross-sectional view along line C-C of a step in making a plurality of semiconductor devices of FIGS. 8A-8B, according to the present disclosure.

(11) FIGS. 10A-10C are schematic diagrams of a top plan view, a cross-sectional view along line B-B, and a cross-sectional view along line C-C of a step in making a plurality of semiconductor devices of FIGS. 8A-8B, according to the present disclosure.

(12) FIGS. 11A-11C are schematic diagrams of a top plan view, a cross-sectional view along line B-B, and a cross-sectional view along line C-C of a step in making a plurality of semiconductor devices of FIGS. 8A-8B, according to the present disclosure.

(13) FIGS. 12A-12C are schematic diagrams of a top plan view, a cross-sectional view along line B-B, and a cross-sectional view along line C-C of a step in making a plurality of semiconductor devices of FIGS. 8A-8B, according to the present disclosure.

DETAILED DESCRIPTION

(14) The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are shown. This present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments.

(15) Referring briefly to FIG. 2, a diagram 25 illustrates normal and shear strain. Normal strain is defined by the following formula:

(16) ${\mathrm{.Math.}}_x=\frac{u_x}{x},{\mathrm{.Math.}}_y=\frac{u_y}{x},{\mathrm{.Math.}}_z=\frac{u_z}{x}.$
Shear strain is defined by the following formula:

(17) ${\mathrm{.Math.}}_{\mathrm{xy}}={\mathrm{.Math.}}_{\mathrm{yx}}=\frac{u_y}{x}+\frac{u_x}{y},{\mathrm{.Math.}}_{\mathrm{yz}}={\mathrm{.Math.}}_{\mathrm{xy}}=\frac{u_y}{z}+\frac{u_z}{y},{\mathrm{.Math.}}_{\mathrm{xz}}={\mathrm{.Math.}}_{\mathrm{zx}}=\frac{u_x}{z}+\frac{u_z}{x}$${\mathrm{.Math.}}_{\mathrm{xy}}=\frac{1}{2}\left(\frac{u_y}{x}+\frac{u_x}{y}\right)$${\mathrm{.Math.}}_{\mathrm{yz}}=\frac{1}{2}\left(\frac{u_y}{z}+\frac{u_z}{y}\right).{\mathrm{.Math.}}_{\mathrm{xz}}=\frac{1}{2}\left(\frac{u_z}{x}+\frac{u_x}{z}\right)$
The transformation from strain tensor to stress tensor is finally obtained following the Hooke's law.

(18) The impact on electrical performance (piezoresistance tensor) with stress is illustrated with silicon (001) surface wafer and [100] or [110] orientation. According to the crystal orientation, the effect of the shear stress on carrier mobility can be important, competitive with normal effect, depending on piezoresistance parameter (carrier type, crystal orientation and material). Table 1 provides a general valid case for any crystal orientation. (See Tables 1-3).

(19) TABLE-US-00001 TABLE 1 Crystal Stress Component ${\left(\frac{}{}\right)}_i=\left(\begin{array}{cccccc}{}_{11}& {}_{12}& {}_{13}& {}_{14}& {}_{15}& {}_{16}\\ {}_{12}& {}_{22}& {}_{23}& {}_{24}& {}_{25}& {}_{26}\\ {}_{13}& {}_{12}& {}_{33}& {}_{34}& {}_{35}& {}_{36}\\ {}_{14}& {}_{24}& {}_{34}& {}_{44}& {}_{45}& {}_{46}\\ {}_{15}& {}_{25}& {}_{35}& {}_{45}& {}_{55}& {}_{56}\\ {}_{16}& {}_{26}& {}_{36}& {}_{46}& {}_{56}& {}_{66}\end{array}\right)\left(\begin{array}{c}{}_{\mathrm{xx}}\\ {}_{\mathrm{yy}}\\ {}_{\mathrm{zz}}\\ {}_{\mathrm{yz}}\\ {}_{\mathrm{xz}}\\ {}_{\mathrm{xy}}\end{array}\right)$

(20) TABLE-US-00002 TABLE 2 Crystal Stress Component Crystal Orientation (001) [100] ${\left(\frac{}{}\right)}_i=\left(\begin{array}{cccccc}{}_{11}& {}_{12}& {}_{13}& 0& 0& 0\\ {}_{12}& {}_{22}& {}_{23}& 0& 0& 0\\ {}_{13}& {}_{12}& {}_{33}& 0& 0& 0\\ 0& 0& 0& {}_{44}& 0& 0\\ 0& 0& 0& 0& {}_{55}& 0\\ 0& 0& 0& 0& 0& {}_{66}\end{array}\right)\left(\begin{array}{c}{}_{\mathrm{xx}}\\ {}_{\mathrm{yy}}\\ {}_{\mathrm{zz}}\\ {}_{\mathrm{yz}}\\ {}_{\mathrm{xz}}\\ {}_{\mathrm{xy}}\end{array}\right)$

(21) TABLE-US-00003 TABLE 3 Silicon Bulk Stress Values (10.sup.11 Pa.sup.1) [The pizo coefficient for the two traditional cases, including that given in Table 2.] 10.sup.11 Pa [100] NSi [100] PSi [110] NSi [110] PSi .sub.11 = .sub.22 102.1 6.6 31.6 71.8 .sub.33 102.1 6.6 102.1 6.6 .sub.12 53.4 1.1 17.6 66.3 .sub.13 = .sub.23 53.4 1.1 53.4 1.1 .sub.44 = .sub.55 13.6 1.1 13.6 1.1 .sub.66 13.6 1.1 77.8 3.85 other 0 0 0 0

(22) As visible on Tables 1-3, .sub.14, .sub.15 and .sub.16 of the first line of the piezo-resistance tensor impact the longitudinal conductivity in presence of shear stress. They are equal to 0 for the standard cases with the channel in [100] and [110] direction, meaning that there is no impact of the shear stress on the mobility. However, two ways are possible to take benefit from shear stress. First, for channel direction between [100] and [110] in (001) plane, i.e. theta between 0 and 45 deg, or for other less classical crystalline orientations, .sub.14, .sub.15 and .sub.16 might not be equal to zero. As a result, the shear component impacts the mobility. Second, as the magnitude of the shear stress increases, because of the strong impact of the shear stress on the band curvature responsible for mobility enhancement, some of the .sub.ij terms can become non null, impacting the contribution of the shear stress on mobility. An indirect illustration is already demonstrated by the impact of the rotation by 45 deg from [100](001) to [110] (001). In that case, the longitudinal stress along [110] becomes a shear stress at the level of the band structure [100] oriented and impact the mobility. This is visible in Table 3 with enhanced values of .sub.11 in the [110] direction for p carrier 71.810.sup.11 Pa instead of 6.610.sup.11 Pa for the [100] direction.

(23) Referring initially to FIGS. 3A and 4A-6A, a semiconductor device 30 according to the present disclosure is now described. The semiconductor device 30 illustratively includes a substrate 38, fins 36a-36b above the substrate and having a channel region 33 therein, and source and drain regions 31-32 adjacent the channel region to generate shear and normal strain on the channel region. In the illustrated embodiment, the semiconductor device 30 comprises a FINFET device, but the teachings herein may be applied to other semiconductor device types.

(24) The source, drain, and channel regions 31-33 are formed from a biaxial stress layer of semiconductor material on the substrate 38. The substrate 38 may comprise a silicon bulk layer or a buried oxide substrate (i.e. a thin BOX). In other embodiments, the substrate 38 may comprise silicon on insulator (SOI) or silicon germanium on insulator (SGOI).

(25) Advantageously, the generation of both normal and shear strain in the channel region 33 is in contrast to the prior art approach in FIG. 1, which generates only normal strain. In particular, the generation of shear strain improves carrier mobility in the channel region 33. In the present disclosure, the shear stress teachings may be effective especially for thin film channel transistors, such as fully depleted SOI (FDSOI), ultra-thin body BOX (UTBB), and FINFETs. In FINFET embodiments, the design thereof has a greater degree of freedom in 3D structures to generate shear stress at the right place in the channel to enhance carrier mobility, thereby improving performance.

(26) The semiconductor device 30 illustratively includes a gate 40 over the channel region. In the illustrated embodiment, the source and drain regions 31-32 have a diamond shape. Of course, in other embodiments, other shapes may be used so long as they create sufficient shear strain in the channel region 33.

(27) Additionally, the semiconductor device 30 illustratively includes a dielectric layer 37 between the substrate 38 and the fins 36a-36b. The substrate 38 and the fins 36a-36b may each comprise silicon, for example. Also, the source and drain regions 31-32 may each comprise silicon. The dielectric layer 37 may comprise silicon dioxide, for example.

(28) Another aspect is directed to a method for making a semiconductor device 30. The method may comprise forming at least one fin 36a-36b above a substrate 38 and having a channel region 33 therein, and forming source and drain regions 31-32 adjacent the channel region to generate shear and normal strain on the channel region.

(29) Referring now to FIGS. 4A-4C, the fins 36a-36b are formed on the dielectric layer 37, which is over the substrate 38. Subsequently, a mask layer 35 is formed over the fins 36a-36b. The mask layer 35 may comprise a silicon nitride layer, for example. Referring in particular to FIGS. 5A-5C, the gate 40 is formed on the fins 36a-36b. The gate 40 may comprise a plurality of layers comprising at least a dielectric layer, an electrically conductive layer forming a gate contact, and a resist layer.

(30) Referring now to FIG. 6A, an illustrative example of the semiconductor device 30 is shown with strain indicator arrows 41a-41b (shear strain 41a, normal strain 41b). The extension of the shear strain in the channel region 33 is defined by the following formula:

(31) $E_{\mathrm{Fin}}=\frac{D_{\mathrm{Fin}}}{\sqrt{2}};$
where E.sub.Fin=extension of the shear strain in the channel region, on both sides, which may be longer than the channel region; and D.sub.fin is Fin thickness. Here, the shear strain 41a is illustratively at 45 degrees, but other angles are possible.

(32) Advantageously, the stress in the channel region 33 is obtained after shape forming for the source and drain regions 31-32. There is no need for complex epitaxial processes in the source and drain regions 31-32 to obtain the strain. Several integrations are possible, such as Fin First (formed before the dummy gate patterning) or after the gate patterning.

(33) Referring now additionally to FIGS. 3B and 6B, another embodiment of the semiconductor device 30 is now described. In this embodiment of the semiconductor device 30, those elements already discussed above with respect to FIGS. 3A and 4A-6A are given prime notation and most require no further discussion herein. This embodiment differs from the previous embodiment in that this semiconductor device 30 has source and drain regions 31-32 with a Y-shape (i.e. defining a dog bone shape). In particular, the source and drain regions 31-32 each have a pair of arms extending in opposite directions, which create shear strain on the channel region 33.

(34) Referring now to FIGS. 7A-7C, several examples of heavy metal deposition layer stacks are shown. The diagrams 50-53 illustrate several embodiments for forming the semiconductor device 30. These diagrams 50-53 illustrate the possibility of using different stressed channel materials (to replace region 30) with strained SOI, strained SGOI as well with SiGe layer, III-V or any material epitaxially grown on silicon substrate to form the channel.

(35) Referring now to FIGS. 8A-12C, another semiconductor device 70a-70d according to the present disclosure is now described. The semiconductor device 70a-70d illustratively includes a substrate 81, a plurality of fins 83a-83c above the substrate and having a channel region 73 therein, source and drain regions 71-72 adjacent the channel region, and a gate 84a-84d over the channel region. Each of the plurality of fins 83a-83c may be canted with respect to the source and drain regions 71-72 to generate shear and normal strain on the channel region 73. In FIG. 8B, the semiconductor device 30 is shown with shear strain indicator arrows 86. In the illustrated embodiment, the semiconductor device 70a-70d comprises a FINFET device, but the teachings herein may be applied to other semiconductor device types.

(36) In the illustrated embodiment, each of the fins 83a-83c is canted at an angle of 45 degrees with respect to the source and drain regions 71-72. In other embodiments, each of the fins 83a-83c may be canted at an angle less than 45 degrees with respect to the source and drain regions 71-72, or in the range of 22.5-67.5 degrees or for improved performance, in the range of 40-50 degrees.

(37) Additionally, the semiconductor device 70a-70d illustratively includes a dielectric layer 82 between the substrate 81 and the plurality of fins 83a-83c. The substrate 81 and the plurality of fins 83a-83c may each comprise silicon, for example. For example, the source and drain regions 71-72 may comprise silicon germanium. Also, the dielectric layer 82 may comprise silicon dioxide.

(38) Another aspect is directed to a method making a semiconductor device 70a-70d. The method may comprise forming at least one fin 83a-83c above a substrate 81 and having a channel region 73 therein, forming source and drain regions 71-72 adjacent the channel region, and forming a gate 84a-84d over the channel region, the at least one fin being canted with respect to the source and drain regions to generate shear and normal strain on the channel region.

(39) Referring in particular to FIGS. 9A-9C, the method illustratively includes forming the plurality of fins 83a-83c on the dielectric layer 82, which is above the substrate 81. In FIGS. 10A-10C, the gate 84a-84d is formed on the fins 83a-83c and the dielectric layer 82. In FIGS. 11A-11C, the recesses for the source and drain regions 71-72 are formed during an etching step. In FIGS. 12A-12C, the source and drain regions 71-72 are formed from an epitaxial layer 85a-85c. The epitaxial layer 85a-85c may comprise silicon germanium, for example.

(40) Advantageously, the method for making the semiconductor device 70a-70d is a self-aligned process, i.e. no additional mask layers are necessary. Moreover, the semiconductor device 70a-70d may also work if the fins 83a-83c are already intrinsically strained (e.g. SGOI, silicon germanium fin, SSOI etc.). In that case, the shear is added to the standard longitudinal stress in the fin coming from the intrinsic strain and brings more efficiency. Also, this method of making a semiconductor device 70a-70d could help to increase the surface for source-drain stressor for a given gate pitch.

(41) A fin field-effect transistor (FINFET) semiconductor device comprising: a substrate; a plurality of fins above said substrate, each fin having a channel region therein; and a plurality a source and drain regions respectively adjacent the channel regions to generate shear and normal strain on the channel regions. The FINFET semiconductor device further comprising a plurality of gates respectively over the channel regions. The plurality of source and drain regions have a diamond shape. The plurality of source and drain regions have a Y-shape.

(42) A method for making a semiconductor device comprising: forming at least one fin above a substrate and having a channel region therein; forming source and drain regions adjacent the channel region to generate shear and normal strain on the channel region; and forming a gate over the channel region. The method includes forming source and drain regions have a diamond shape. The method includes forming source and drain regions have a Y-shape. The method includes forming a dielectric layer between the substrate and the at least one fin. The dielectric layer comprises silicon dioxide. The substrate and the at least one fin each comprises silicon.

(43) The source and drain regions each comprises silicon. A fin field-effect transistor (FINFET) semiconductor device comprising: a substrate; a plurality of fins above said substrate, each fin having a channel region therein; a plurality of source and drain regions respectively adjacent the channel regions; and a plurality of gates respectively over the channel regions; said plurality of fins being canted with respect to said plurality of source and drain regions to generate shear and normal strain on the channel regions. The plurality of fins is canted at an angle in a range of 22.5-67.5 degrees with respect to said plurality of source and drain regions. The plurality of fins is canted at an angle in a range of 40-50 degrees with respect to said plurality of source and drain regions. The FINFET semiconductor device includes a dielectric layer between said substrate and said plurality of fins. The dielectric layer comprises silicon dioxide. The substrate and said plurality of fins each comprises silicon. The plurality of source and drain regions comprise silicon germanium.

(44) The method may further include forming a dielectric layer between the substrate and the at least one fin, the substrate and the at least one fin each comprises silicon, and the source and drain regions comprise silicon germanium.

(45) Many modifications and other embodiments of the present disclosure will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the present disclosure is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.