STANDARD CELL HAVING VERTICAL TRANSISTORS

Abstract

The disclosed technology generally relates to semiconductor devices, and more particularly to a standard cell semiconductor device comprising transistors having vertical channels and a common gate. In one aspect, a standard cell semiconductor device comprises a substrate, a unit cell having a first transistor and a second transistor, a gate layer common to the first and second transistor, and a set of routing tracks for contacting the first and second transistor. Each one of the first and second transistors is formed of a stack of layers arranged between at least some of the routing tracks and the substrate, wherein each stack comprises a bottom terminal arranged on the substrate, a channel arranged on the bottom terminal and a top terminal arranged on the channel. The channel of the first transistor is an N-type channel, and the channel of the second transistor is a P-type channel. Further, the routing tracks comprises a pair of power routing tracks arranged on opposite sides of the unit cell and adapted to contact the top terminal of the first and second transistors, and a gate track arranged between the pair of power routing tracks and adapted to contact the gate layer at a position beside the unit cell.

Claims

1. A standard cell semiconductor device, comprising: a substrate; a unit cell having a first transistor and a second transistor; a gate layer common to the first and second transistors; and a set of routing tracks contacting the first and second transistors, wherein each of the first and second transistors is formed of a stack of layers arranged between at least some of the routing tracks and the substrate, wherein the stack of layers comprises: a bottom terminal arranged over the substrate, a top terminal arranged over the bottom terminal, and a channel extending vertically in a lengthwise direction to contact the bottom terminal and the top terminal, wherein the channel of the stack of layers of the first transistor is an N-type channel, and wherein the channel of the stack of layers of second transistor is a P-type channel, wherein the gate layer at least partly covers the N-type channel and the P-type channel, and wherein the routing tracks comprise: a pair of power routing tracks arranged on opposite lateral sides of the unit cell and contacting the top terminal of each of the first and second transistors, and a gate track arranged laterally between the pair of power routing tracks and contacting the gate layer at a position outside the unit cell.

2. The standard cell semiconductor device according to claim 1, wherein the first transistor and the second transistor are arranged beside each other in a direction orthogonal to a direction of extension of the pair of power routing tracks.

3. The standard cell semiconductor device according to claim 1, wherein the first transistor and the second transistor are arranged beside each other in a direction parallel to a direction of extension of the pair of routing tracks.

4. The standard cell semiconductor device according to claim 1: wherein the first transistor comprises a plurality of N-type channels arranged in a first row, wherein the second transistor comprises a plurality of P-type channels arranged in a second row, and wherein the first row and the second row are parallel to and oppose each other in a direction orthogonal to row directions of the first and second rows.

5. The standard cell semiconductor device according to claim 1, wherein the channel is a nanowire.

6. The standard cell semiconductor device according to claim 1, wherein the pair of power routing tracks and the gate track form a three tracks (3T) standard cell.

7. The standard cell semiconductor device according to claim 1, comprising a pair of gate tracks that, in combination with the pair of power routing tracks, form a four tracks (4T) standard cell.

8. The standard cell semiconductor device according to claim 1, comprising two pairs of power routing tracks contacting the top terminal of the first and second transistors, and a pair of gate tracks that, in combination with the two pairs of power routing tracks, form a six tracks (6T) standard cell.

9. The standard cell semiconductor device according to claim 1, further comprising a buried power rail electrically contacting the bottom terminal.

10. The standard cell semiconductor device according to claim 1, wherein the first transistor and the second transistor are gate-all-around transistors.

11. A standard cell semiconductor device, comprising a substrate; a row of unit cells, each of the unit cells having a first transistor and a second transistor connected by a common gate layer; and a set of routing tracks contacting the unit cells, wherein each of the first and second transistors is formed of a stack of layers arranged between the routing tracks and the substrate, wherein the stack of layers comprises: a bottom terminal arranged over the substrate, a top terminal arranged over the bottom terminal, and a channel extending in a length direction to contact the bottom terminal and the top terminal, wherein the channel of the first transistor of each of the unit cells is an N-type channel, and wherein the channel of the second transistor of each of the unit cells is a P-type channel, wherein the gate layer of each of the unit cells at least partly covers the N-type channel and the P-type channel of the each of the unit cells, and wherein the routing tracks comprise: a pair of power routing tracks arranged on opposite lateral sides of the row of unit cells and contacting the top terminal of each of the first and second transistors, and a gate track arranged laterally between the pair of power routing tracks and contacting the gate layer of each of the unit cells at a position between the unit cells.

12. The standard cell semiconductor device according to claim 11, wherein the first transistor and the second transistor are arranged beside each other in a direction orthogonal to a direction of extension of the pair of power routing tracks.

13. The standard cell semiconductor device according to claim 11, wherein the first transistor and the second transistor are arranged beside each other in a direction parallel to a direction of extension of the pair of routing tracks.

14. The standard cell semiconductor device according to claim 11: wherein the first transistor comprises a plurality of N-type channels arranged in a first row, wherein the second transistor comprises a plurality of P-type channels arranged in second row, and wherein the first row and the second row are parallel to and oppose each other in a direction orthogonal to row directions of the first and second rows.

15. The standard cell semiconductor device according to claim 11, wherein the channel is a nanowire.

16. The standard cell semiconductor device according to claim 11, wherein the pair of power routing tracks and the gate track form a three tracks (3T) standard cell.

17. The standard cell semiconductor device according to claim 11, comprising a pair of gate tracks that, in combination with the pair of power routing tracks, form a four tracks (4T) standard cell.

18. The standard cell semiconductor device according to claim 11, comprising two pairs of power routing tracks contacting the top terminal of the first and second transistors of a respective unit cell, and a pair of gate tracks that, in combination with the two pairs of power routing tracks form a six tracks (6T) standard cell.

19. The standard cell semiconductor device according to claim 11, further comprising a buried power rail contacting the bottom terminal.

20. The standard cell semiconductor device according to claim 11, wherein the first transistor and the second transistor are gate-all-around transistors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above, as well as additional objects, features and advantages of the disclosed technology, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the disclosed technology, with reference to the appended drawings.

[0033] FIG. 1 schematically illustrates a perspective view of a unit cell, comprising a first transistor and a second transistor with a common gate layer, according to some embodiments.

[0034] FIG. 2 schematically illustrates a plan view of a standard cell semiconductor device comprising a unit cell, according to some embodiments.

[0035] FIG. 3 schematically illustrates a plan view of a standard cell semiconductor device comprising a row of unit cells, according to some embodiments.

[0036] FIG. 4 schematically illustrates a plan view of a standard cell semiconductor device having a row of unit cells, according to some other embodiments.

[0037] As illustrated in the figures, the sizes of the elements, features and other structures may be exaggerated or not depicted proportionally for illustrative purposes. Thus, the figures are provided to illustrate the general elements of the embodiments.

[0038] In the drawings, like reference numerals will be used for like elements unless stated otherwise.

DETAILED DESCRIPTION OF CERTAIN ILLUSTRATIVE EMBODIMENTS

[0039] FIG. 1 schematically illustrates a perspective view of a unit cell 10, according to some embodiments. The unit cell 10 comprises a first vertical transistor 111 and a second vertical transistor 112. Each of the transistors 111, 112 may be formed of a vertical stack formed on, or above, a substrate 110. In various illustrations, for clarity, a portion of the substrate 110 on which the unit cell 10 is arranged may be shown. However, it will be appreciated that the substrate 110 may accordingly extend laterally/horizontally beyond the illustrated portion. The substrate 110 may for instance be a (bulk) silicon substrate, a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GeOI) substrate or a dielectric substrate, to name a few examples.

[0040] As described herein, a nanowire refers to an elongated structure having a cross-sectional dimension that is about or smaller than about 100 nm. For example, a nanowire having a cylindrical shape can have a cross-sectional diameter that is about or smaller than about 100 nm.

[0041] Still referring to FIG. 1, the first transistor 111 may include a vertically extending channel 140, such as e.g., a nanowire 140, which may be doped with a dopant of first type, e.g., n-type. The channel 140 may include first and second source/drain (regions) connected to a respective top/bottom terminal or electrode 130, 150 arranged on opposite sides of the channel 140. The bottom electrode 130 may be separated from the substrate 110 by a dielectric (not shown). The bottom electrode 130 may hence be isolated from the substrate 110. The bottom electrodes 130 may also be arranged directly on a dielectric portion of the substrate 110, for instance a dielectric layer such or an oxide formed on the substrate 110.

[0042] The second transistor 112 may be similarly configured as the first transistor 111, but doped with a dopant of second type, e.g., p-type channel 140 extending between the top/bottom electrodes 130, 150. Thus, the first and second transistor 111, 112 may form a complementary transistor pair or a CMOS structure, according to some embodiments.

[0043] The channel 140 may comprise one or several nanostructures, such as e.g., a row of three parallel nanowires 140 as indicated in the example illustrated in FIG. 1.

[0044] The unit cell 10 may further include a gate layer 120 which serves as a gate electrode for the first transistor 111 and the for second transistor 112. In some embodiments, the gate layer 120 may be common gate electrode for both transistors 111, 112, which thereby may be electrically connected to each other to form the complementary transistor pair. The gate electrode 120 may enclose the channel 140 at least along a longitudinal portion thereof, e.g., to form the first and second transistors 111, 112, each of which may be a gate-all-around field effect transistor (GAAFET) comprising a gate-all-around channel, which may be a nanowire channel.

[0045] The gate layer 120 may include one or more metals (or alloys thereof), for instance Ti, W, T or Al. Further, a gate dielectric (not shown in the figure) may be arranged between the channel 140 and the gate layer 120. The gate dielectric may include a material such as an oxide, for instance a SiO.sub.2, and/or a high-k (e.g., k greater than about 3.9) dielectric, for instance HfO.sub.2 or ZrO.sub.2.

[0046] The bottom electrode 130 may be connected to a buried power line 170, which e.g., may be arranged in the substrate 110 or between the substrate 110 and the transistor 111, 112 so as to connect the source/drain of the transistor to electrical power. The bottom electrode 130 and the power line 170 may be separated by an intermediate dielectric layer (not shown in FIG. 1), which may be provided with openings or contact structures at a position where an electrical connection maybe formed between the bottom electrode 130 and the power line 170. The contact structures may be formed in or through the intermediate dielectric using a suitable lithographic patterning process.

[0047] FIG. 2 schematically illustrates a plan view of a standard cell semiconductor device 1 comprising a unit cell 10, according to some embodiments. The unit cell 10 may be similarly configured in some aspects as the unit cell 10 discussed above in connection with FIG. 1. The standard cell 1 comprises a pair of (unidirectional) power routing tracks T1, T2 arranged at the top and the bottom of the standard cell such that the unit cell 10 may be arranged vertically therebetween. The first transistor 111 and the second transistor 112 of the unit cell 10 may be arranged adjacently in a row, e.g., consecutively, between the top power routing track T1 and the bottom power routing track T2. As indicated in FIG. 2, the top electrode 150 of the first transistor 111 may be connected to the top power routing track T1 by an interconnect structure 160, such as an electrical via 160. Similarly, the top electrode 150 of the second transistor 112 may be connected to the bottom power routing track T2 by e.g., a via connection 160. The top power routing track T1 may e.g., connect the complementary transistor structure to V.sub.DD, whereas the bottom power routing track T2 may connect the transistor structure to V.sub.SS. The bottom electrode 130 of each transistor T1, T2 may be connected to a buried power line (not shown in FIG. 2).

[0048] Still referring to FIG. 2, a gate track T3 may be provided between the pair of power routing tracks T1, T2 for contacting the common gate layer 130 of the unit cell 10. The position of the gate track T3 is merely indicated by dashed lines in FIG. 2. The distance between the tracks may be characterized in terms of a number of metal-pitches (MP) or routing tracks, where a metal pitch may represent a center-to-center distance between tracks having a minimum width and a minimum spacing. In the example shown in FIG. 2, the distance between the tracks T1 and T3 may therefore be expressed as 1MP, whereas the distance between tracks T3 and T2 may be 2MP, resulting in a cell width or height of 3MP. Thus, the illustrated standard cell may be referred to as a three track (3T) standard cell. However, embodiments are not so limited, and the standard cell may be configured to have a width or height corresponding to 4 or more routing tracks or MPs.

[0049] In some embodiments, the common gate layer 130 may extend beyond the first and second transistors T1, T2 in a lateral direction, e.g., to a side of the unit extending between the pair of power routing tracks T1, T2. This allows for the gate layer 130 to be contacted at a position beside the unit cell 10, i.e., at a position outside the transistors T1, T2 rather than between them. The gate track T3 may contact or access the gate layer by means of a via or an interconnect structure 160.

[0050] FIG. 3 schematically illustrates a plan view of a standard cell semiconductor device, according to some embodiments. The illustrated standard cell semiconductor device 1 may be similarly configured as the device in FIG. 2 in some aspects, comprising a row of e.g., three unit cells 11, 12, 13. Each one of the unit cells 11, 12, 13 may be connected, indirectly or directly, to the top power routing track T1 and the bottom power routing track T2. In the specific example illustrated, the second unit cell 12 may be connected directly to the top power routing track T1 and the bottom power routing track T2 through the interconnects 160. Further, the first unit cell 11 may be connected directly to the top power routing track T1 and indirectly, via the second unit cell 12, to the bottom power routing track T2. Similarly, the third unit cell 13 may be directly connected to the bottom power routing track T2 and indirectly, via the second unit cell 12, to the top power routing track T1. The distance between the tracks Ti and T3 may be 1MP and the distance between T3 and T2 2MP, giving a total cell width or height of 3MP. Hence, the cell is a 3T cell (having a height corresponding to 4 routing tracks).

[0051] FIG. 4 schematically illustrates a plan view of a standard cell semiconductor device, according to some other embodiments. The illustrated standard cell semiconductor device 1 comprising a plurality of unit cells 11, 12, 13 may be similarly configured as the unit cells described in connection with FIGS. 1 to 3 in some aspects. However, the unit cells according to the present example may be oriented such that the first and second transistor 111, 112 of each unit cell 11, 12, 13 may be oriented beside each other in a direction parallel to the routing tracks T1-T6 of the standard cell. This allows for the metal layers, i.e. the top/bottom electrodes and the gate contacts, to be oriented in a regular, unidirectional manner which is easier to print.

[0052] The top electrode of the first transistor 111 of the first, second and third unit cells 11, 12, 13 may be interconnected by an interconnecting track T6, and directly or indirectly supplied with e.g., V.sub.DD from the top power routing track T1 through interconnect 160. Further, the top electrode of the second transistor of the first and the second unit cells 11, 12 may be interconnected to each other by interconnecting track T5, and supplied with e.g., V.sub.SS from the bottom power routing track an interconnecting structure 160. The gate electrodes, or gate layer 120, of the unit cells 11, 12, 13 may be accessed at positions beside the unit cells, i.e., at positions between adjacent unit cells of the device 1. The positions of the gate layer contacting points may be defined by a first and a second gate track T3, T4. As indicated in the present figure, the distance between tracks T1 and T5 is 1MP, between T5 and T3 2MP, between T3 and T6 2MP, and between T6 and T2 1MP, giving a total cell height of 6MP. Thus, the present standard cell may be referred to as a six track (6T) standard cell, requiring six routing tracks for connecting the transistors of the device and having a height corresponding to seven routing tracks.

[0053] In the above, the inventive concept has mainly been described with reference to a limited number of examples. However, as is readily appreciated by a person skilled in the art, other examples than the ones disclosed above are equally possible within the scope of the inventive concept as defined by the appended claims. Variations to the disclosed embodiments may be understood and effected by the skilled person in practicing the inventive concept, from a study of the drawings, the disclosure and the appended claims.