阅读说明：本技术 形成自对准栅极及源/漏接触以及所得装置 (Forming self-aligned gate and source/drain contacts and resulting devices ) 是由 朱利安·弗罗吉尔 谢瑞龙 朴灿柔 程慷果 于 2019-07-15 设计创作，主要内容包括：本发明涉及形成自对准栅极及源/漏接触以及所得装置，其中，一种方法包括：形成主动层；在该主动层的沟道区上方形成栅极结构；邻近该栅极结构形成侧间隙壁；邻近该侧间隙壁形成第一介电层；凹入该栅极结构以界定栅极空腔；在该栅极空腔中形成内间隙壁；在该栅极空腔中形成覆盖层；凹入该第一介电层及该侧间隙壁，以暴露该覆盖层的侧壁表面；移除该内间隙壁，以界定第一间隙壁空腔；在该间隙壁空腔中并接触该覆盖层的侧壁表面形成上间隙壁；在该上间隙壁及该覆盖层上方形成第二介电层；以及形成至少部分嵌入该第二介电层中并接触该上间隙壁的表面的第一接触结构。(The invention relates to forming self-aligned gate and source/drain contacts and resulting devices, wherein a method comprises: forming an active layer; forming a gate structure over the channel region of the active layer; forming a side spacer adjacent to the gate structure; forming a first dielectric layer adjacent to the sidewall spacers; recessing the gate structure to define a gate cavity; forming an inner spacer in the gate cavity; forming a capping layer in the gate cavity; recessing the first dielectric layer and the sidewall spacers to expose sidewall surfaces of the capping layer; removing the inner spacer to define a first spacer cavity; forming an upper spacer in the spacer cavity and contacting a sidewall surface of the capping layer; forming a second dielectric layer over the upper spacer and the capping layer; and forming a first contact structure at least partially embedded in the second dielectric layer and contacting a surface of the upper spacer.)

1. An apparatus, comprising:

an active layer;

a gate structure located over the channel region of the active layer;

a side spacer located adjacent to the gate structure;

a capping layer over the gate structure;

an upper spacer contacting a sidewall surface of the capping layer and a portion of an upper surface of the gate structure;

a second dielectric layer over the top spacer and the capping layer; and

and a first contact structure at least partially embedded in the second dielectric layer and contacting the surface of the upper spacer.

2. The apparatus of claim 1, further comprising:

a source/drain region in the active layer adjacent to the side spacer; and

and a lower source/drain contact structure contacting the source/drain region, wherein the first contact structure contacts the outer surface of the upper spacer and the lower source/drain contact structure.

3. The device of claim 1, wherein the first contact structure contacts an inner surface of the upper spacer and the gate structure.

4. The apparatus of claim 1, wherein the side spacer includes an air gap defined therein.

5. A method, comprising:

forming an active layer;

forming a gate structure over the channel region of the active layer;

forming a side spacer adjacent to the gate structure;

forming a first dielectric layer adjacent to the sidewall spacers;

recessing the gate structure to define a gate cavity;

forming an inner spacer in the gate cavity;

forming a capping layer in the gate cavity adjacent to the inner spacer;

recessing the first dielectric layer and the sidewall spacers to expose sidewall surfaces of the capping layer;

removing the inner spacer to define a first spacer cavity adjacent to the capping layer;

forming an upper spacer in the spacer cavity and contacting a sidewall surface of the capping layer;

forming a second dielectric layer over the upper spacer and the capping layer; and

a first contact structure is formed at least partially embedded in the second dielectric layer and contacting a surface of the upper spacer.

6. The method of claim 5, further comprising:

forming source/drain regions in the active layer adjacent to the side spacers;

forming a lower source/drain contact structure contacting the source/drain region;

removing a first portion of the second dielectric layer to expose the lower source/drain contact structure and an outer surface of the upper spacer and define a first contact cavity; and

forming the first contact structure in the first contact cavity, the first contact structure contacting the outer surface of the upper spacer and the lower source/drain contact structure.

7. The method of claim 6, further comprising:

removing a second portion of the second dielectric layer to expose the capping layer;

removing the capping layer to expose an inner surface of the upper spacer and the gate structure, thereby defining a second contact cavity; and

a second contact structure is formed in the second contact cavity, the second contact structure contacting the inner surface of the upper spacer and the gate structure.

8. The method of claim 5, further comprising:

removing a first portion of the second dielectric layer to expose the capping layer;

removing the capping layer to expose an inner surface of the upper spacer and the gate structure, thereby defining a first contact cavity; and

forming the first contact structure in the first contact cavity, the first contact structure contacting the inner surface of the upper spacer and the gate structure.

9. The method of claim 5, further comprising:

removing the side spacers before removing the inner spacers to define a lower spacer cavity; and

a dielectric material is formed in at least an upper portion of the lower spacer cavity to define an air gap in the lower spacer cavity adjacent the gate structure.

10. The method of claim 9, wherein said dielectric material lines said lower spacer cavity.

11. The method of claim 9, further comprising:

forming source/drain regions in the fin adjacent to the side spacers;

forming a lower source/drain contact structure contacting the source/drain region;

removing a first portion of the second dielectric layer to expose the lower source/drain contact structure and an outer surface of the upper spacer and define a first contact cavity; and

forming the first contact structure in the first contact cavity, the first contact structure contacting the outer surface of the upper spacer and the lower source/drain contact structure.

12. The method of claim 11, further comprising:

forming an intermediate source/drain contact structure over the lower source/drain contact structure, the intermediate source/drain contact structure exposing an upper portion of the side spacer;

removing the side spacers after forming the intermediate source/drain contact structure; and

the first contact structure is formed to contact the intermediate source/drain contact structure.

13. The method of claim 12, wherein the intermediate source/drain contact structure and the first contact structure comprise the same material.

14. A method, comprising:

forming an active layer;

forming a gate structure over the channel region of the active layer;

forming a side spacer adjacent to the gate structure;

forming source/drain regions in the active layer adjacent to the side spacers;

forming a first dielectric layer adjacent to the sidewall spacers;

recessing the gate structure to define a gate cavity;

forming an inner spacer in the gate cavity;

forming a capping layer in the gate cavity adjacent to the inner spacer;

recessing the first dielectric layer and the sidewall spacers to expose sidewall surfaces of the capping layer;

forming a source/drain contact structure adjacent to the side spacer and contacting the source/drain region;

removing the side spacer to define a lower spacer cavity;

forming a dielectric material in at least an upper portion of the lower spacer cavity to define an air gap in the lower spacer cavity adjacent the gate structure;

removing the inner spacer to define a first spacer cavity adjacent to the capping layer;

forming an upper spacer in the spacer cavity and contacting a sidewall surface of the capping layer;

forming a second dielectric layer over the upper spacer and the capping layer; and

a first contact structure is formed at least partially embedded in the second dielectric layer and contacting a surface of the upper spacer.

15. The method of claim 14, further comprising:

removing a first portion of the second dielectric layer to expose the lower source/drain contact structure and an outer surface of the upper spacer and define a first contact cavity; and

forming the first contact structure in the first contact cavity, the first contact structure contacting the outer surface of the upper spacer and the lower source/drain contact structure.

16. The method of claim 15, further comprising:

removing a second portion of the second dielectric layer to expose the capping layer;

removing the capping layer to expose an inner surface of the upper spacer and the gate structure, thereby defining a second contact cavity; and

a second contact structure is formed in the second contact cavity, the second contact structure contacting the inner surface of the upper spacer and the gate structure.

17. The method of claim 14, further comprising:

removing a first portion of the second dielectric layer to expose the capping layer;

removing the capping layer to expose an inner surface of the upper spacer and the gate structure, thereby defining a first contact cavity; and

forming the first contact structure in the first contact cavity, the first contact structure contacting the inner surface of the upper spacer and the gate structure.

18. The method of claim 14, wherein said dielectric material lines said lower spacer cavity.

19. The method of claim 14, further comprising:

forming an intermediate source/drain contact structure over the lower source/drain contact structure, the intermediate source/drain contact structure exposing an upper portion of the side spacer;

removing the side spacers after forming the intermediate source/drain contact structure; and

the first contact structure is formed to contact the intermediate source/drain contact structure.

20. The method of claim 19, wherein the intermediate source/drain contact structure and the first contact structure comprise the same material.

Technical Field

The present application relates generally to the fabrication of semiconductor devices, and more particularly to a method for forming self-aligned gate and source/drain contacts using sacrificial gate capping spacers (sacrificial gate cap spacers) and the resulting device.

Background

Generally, due to the large number of semiconductor devices (i.e., circuit elements such as transistors, resistors, capacitors, etc.) and the required complex layout in current integrated circuits, the electrical connections or "wiring" of the various semiconductor devices such as transistors, capacitors, etc. cannot be established within the same device level at which they are fabricated. Thus, various electrical connections are formed in a metallization system that includes a plurality of stacked "metallization layers" formed above the device level of the product, which constitute the overall circuit pattern of the Integrated Circuit (IC) product.

For normal operation, for a typical transistor, separate conductive paths are formed for the conductive gate structure, source region, and drain region of the transistor. Part of the process includes forming what are commonly referred to as device level contacts, i.e., a plurality of so-called "CA contact" structures for establishing electrical connection with the source/drain regions of the transistor device, and a gate contact structure (sometimes referred to as a "CB contact" structure) for establishing electrical connection with the gate structure of the transistor device. The CB gate contact is typically located vertically above the isolation material surrounding the transistor device, i.e., the CB gate contact is typically not located above the active region, but in some advanced architectures it may be located above the active region.

The CB gate contact is typically located over an isolation region to avoid or reduce the probability of forming an electrical short between the CB gate contact and a conductive source/drain structure (e.g., a Trench Silicide (TS) structure) formed in the source/drain region of the transistor adjacent to the gate structure of the transistor. Typically, there are also design rules that dictate the minimum spacing that must be maintained between the CB gate contact and the conductive source/drain structure in an attempt to prevent such electrical shorts. Unfortunately, there is an area penalty associated with the requirement that the CB gate contact be located only over the isolation region. Furthermore, an insulating material (typically in the form of at least side spacers) is located between the gate structure and the conductive source/drain structures located on opposite sides of the gate structure. The spacers are typically made of silicon nitride having a relatively high k value, e.g., about 7-8. Due to this physical configuration of the transistor, a gate-to-contact (gate-to-contact) capacitor is defined, wherein the gate electrode serves as a conductive plate of the capacitor, the conductive source/drain structure serves as another conductive plate of the capacitor, and a spacer is located between the two conductive plates. This gate-contact capacitor is parasitic in nature because it must be charged and discharged each time the transistor device is turned on (on) and off (off), all of which results in delaying the switching speed of the device.

The present application provides various methods and resulting devices that can avoid, or at least reduce, the effects of one or more of the above-described problems.

Disclosure of Invention

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

The present application relates generally to various methods of forming self-aligned gate and source/drain contacts using a sacrificial gate overlying a spacer, and the resulting devices. An example apparatus includes: among other things, an active layer, a gate structure over a channel region of the active layer, a side spacer adjacent the gate structure, a capping layer over the gate structure, an upper spacer (upper spacer) contacting a sidewall surface of the capping layer and a portion of an upper surface of the gate structure, a second dielectric layer over the upper spacer and the capping layer, and a first contact structure at least partially embedded in the second dielectric layer and contacting a surface of the upper spacer.

An example method includes: forming, among other things, an active layer; forming a gate structure over the channel region of the active layer; forming a side spacer adjacent to the gate structure; forming a first dielectric layer adjacent to the sidewall spacers; recessing the gate structure to define a gate cavity (cavity); forming an inner spacer in the gate cavity; and forming a capping layer in the gate cavity adjacent to the inner spacer. The method further comprises the following steps: recessing the first dielectric layer and the sidewall spacers to expose sidewall surfaces of the capping layer; removing the inner spacer to define a first spacer cavity adjacent to the capping layer; forming an upper spacer in the spacer cavity and contacting a sidewall surface of the capping layer; forming a second dielectric layer over the upper spacer and the capping layer; and forming a first contact structure at least partially embedded in the second dielectric layer and contacting a surface of the upper spacer.

Another example method includes: forming, among other things, an active layer; forming a gate structure over the channel region of the active layer; forming a side spacer adjacent to the gate structure; forming source/drain regions in the active layer adjacent to the side spacers; forming a first dielectric layer adjacent to the sidewall spacers; recessing the gate structure to define a gate cavity; forming an inner spacer in the gate cavity; and forming a capping layer in the gate cavity adjacent to the inner spacer. The method further comprises the following steps: recessing the first dielectric layer and the sidewall spacers to expose sidewall surfaces of the capping layer; forming a source/drain contact structure adjacent to the side spacer and contacting the source/drain region; removing the side spacer to define a lower spacer cavity (lower spacer cavity); forming a dielectric material in at least an upper portion of the lower spacer cavity to define an air gap in the lower spacer cavity adjacent the gate structure; removing the inner spacer to define a first spacer cavity adjacent to the capping layer; forming an upper spacer in the spacer cavity and contacting a sidewall surface of the capping layer; forming a second dielectric layer over the upper spacer and the capping layer; and forming a first contact structure at least partially embedded in the second dielectric layer and contacting a surface of the upper spacer.

Drawings

The present application may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:

FIGS. 1A-1J illustrate various methods for forming self-aligned gate and source/drain contacts using sacrificial gate capping spacers and the resulting devices disclosed herein; and

figures 2A-2E show various methods for forming self-aligned gate and source/drain contacts using sacrificial gate overlying spacer walls, and the resulting devices disclosed herein.

While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Detailed Description

Various exemplary embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The inventive subject matter will now be described with reference to the drawings. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present application with details that are well known to those skilled in the art, but are nevertheless included to explain and explain examples of the present application. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.

The present application relates generally to various methods and resulting devices for forming self-aligned gate and source/drain contacts using a sacrificial gate overlying a spacer. After a complete reading of the present application, it will be readily apparent to those skilled in the art that the present method can be used in a variety of devices including, but not limited to, logic devices, memory devices, and the like. Various exemplary embodiments of the methods and apparatus disclosed herein will now be described in more detail with reference to the accompanying drawings.

Fig. 1A-1J illustrate various methods for forming self-aligned gate and source/drain contacts in a semiconductor device 100 using a sacrificial gate overlying a spacer. In the exemplary embodiment, these contacts are formed for finFET devices, however, application of these techniques is not limited to a particular type of device and they may be applied to other structures built on bulk, SOI, or hybrid substrates, such as planar transistors, gate-all-around (GAA) nanowire transistors, GAA nanosheet transistors, and the like. Fig. 1A-1G and 1I-1J show cross-sectional views of a substrate 105 (along the gate length of the device 100, i.e., along the direction of current flow when the device is operating) with fins 110 (as defined by the dashed lines) defined in the substrate 105. A gate structure 115, including a gate insulating layer (e.g., a high-k material such as hafnium oxide) and a metal gate electrode (e.g., comprising one or more layers such as a barrier layer, a work function material layer, a seed layer, a conductive fill layer, etc.), not separately shown, is formed over the channel region of fin 110. First sidewall spacers 120 (e.g., SiN, SiOC, etc.) are formed adjacent the gate structure 115. Source/drain regions 125 are formed in trenches defined in fin 110 adjacent to gate structures 115 and side spacers 120 (e.g., epitaxially grown semiconductor material such as silicon germanium, silicon carbon, silicon phosphorous, etc., depending on the particular transistor device type). A dielectric layer 130 (e.g., silicon dioxide, a low-k dielectric material, an ultra-low-k dielectric material, etc.) is formed adjacent to the first sidewall spacers 120.

The finFET device 100 shown herein may be an NMOS or PMOS transistor. In addition, various doped regions, such as halo implant regions, well regions, etc., may be formed in substrate 105, fin 110, or source/drain regions 125, but are not shown in the figures. The substrate 105 may have various configurations, such as the bulk silicon configuration shown. The substrate 105 may also have a silicon-on-insulator (SOI) configuration including a bulk silicon layer, a buried insulating layer, and an active layer, wherein semiconductor devices are formed in and over the active layer. The substrate 105 and/or fin 110 may be formed of silicon or silicon germanium, or it may be made of a material other than silicon, such as germanium. Thus, the term "substrate" or "semiconductor substrate" should be understood to encompass all semiconductor materials and all forms of such materials. The substrate 105 may have different layers. For example, the fins 110 may be formed in a process layer formed above a base layer of the substrate 105.

Fig. 1B shows the device 100 after an etch process is performed to recess the gate structure 115 to define the cover cavity 135 and processes are performed to form inner spacers 140 (e.g., amorphous silicon) on the sidewalls of the cover cavity 135. A conformal deposition process is performed to define a spacer layer in the cap cavity 135 and over the dielectric layer 130, and an anisotropic (anisotropic) etch process is performed to remove horizontal portions of the spacer layer, thereby defining the inner spacers 140.

Fig. 1C shows the device 100 after performing a deposition process to form a capping layer 145 (e.g., silicon nitride) in the capping cavity 135 and a planarization process to remove portions of the capping layer 145 that are outside of the capping cavity 135.

Fig. 1D shows device 100 after one or more etching processes are performed to recess dielectric layer 130, thereby defining contact openings 150 adjacent to side spacers 120 to expose source/drain regions 125. The one or more etching processes also reduce the height of the side spacers 120, thereby exposing the outer sidewall surfaces 140S of the inner spacers 140. Although not visible in fig. 1D, the contact opening 150 extends between adjacent gate structures 115 having side spacers 120. For ease of illustration, the adjacent gate structures 115 are not shown. The one or more etching processes may include: an isotropic (isotropic) etch to selectively recess the dielectric layer 130, followed by a selective anisotropic etch to reduce the height of the side spacers 120; a selective anisotropic etch to reduce the height of the side spacers 120, followed by an isotropic etch to selectively recess the dielectric layer 130 that provides protection to the source/drain regions 125; or an anisotropic etch timed to recess the dielectric layer 130 and reduce the height of the sidewall spacers 120.

Fig. 1E shows device 100 after formation of lower source/drain contact structures 155 (e.g., trench silicide) in contact openings 150. The lower source/drain contact structure 155 may be formed by filling the contact opening 150 and performing an etching process to recess the lower source/drain contact structure 155.

FIG. 1F shows the device 100 after a selective etch process is performed to remove the inner spacers 140, thereby forming spacer cavities 160 between the side spacers 120 and the capping layer 145.

Figure 1G shows the device 100 after performing several processes to form upper spacers 165 (e.g., SiOC or other materials having etch selectivity with respect to the materials of the subsequent ILD dielectric layer and capping layer 145) over the side spacers 120 and in the spacer cavities 160, thereby covering the sidewall surfaces 145S of the capping layer 145. A conformal deposition process is performed to define a spacer layer in the spacer cavity 160 and over the side spacers 120 and the lower source/drain contact structures 155, and an anisotropic etch process is performed to remove portions of the spacer layer over the lower source/drain contact structures 155, thereby defining the upper spacers 165.

Fig. 1H shows a top view of the device 100 in simplified form to show the fins 110 and the gate structure 115. Contact source/drain regions 125 are formed as CA contacts and contact gate structure 115 is formed as a CB contact. The location and number of CA and CB contacts may vary.

Fig. 1I and 1J show the device 100 after performing several processes to form upper source/drain contact structures 170 (i.e., CA contacts) and gate contact structures 175 (i.e., CB contacts), respectively. A deposition process is performed to form dielectric layer 180 and a patterning process (e.g., photolithography and etching) is performed to define contact openings in dielectric layer 180, exposing a portion of lower source/drain contact structure 155 located in the CA region and exposing a portion of capping layer 145 located in the CB region. A selective etch process is performed to remove the exposed portions of the capping layer 145. One or more processes are performed to deposit conductive materials (e.g., liner layers, barrier layers, seed layers, fill materials (tungsten, cobalt), etc.) for the upper source/drain contact structures 170 and the gate contact structures 175. The contact opening to the upper source/drain contact structure 170 is self-aligned with the outer surface 165S1 of the upper spacer 165, and the gate contact structure 175 is self-aligned with the capping layer 145 and the inner surface 165S2 of the upper spacer 165.

Fig. 2A-2E show an alternative embodiment of a method for using the air gap spacer forming means 200. Figure 2A shows the device 200 after a deposition process is performed to form an intermediate source/drain contact structure 205 (e.g., tungsten) over the lower source/drain contact structure 155, beginning at the stage of processing shown for the device 100 in figure 1E. A material for the intermediate source/drain contact structures 205 may be deposited and an etch process may be performed to recess the material until the top of the side spacers 120 are exposed.

Fig. 2B shows the device 200 after a selective etch process is performed to remove the side spacers 120, thereby defining the lower spacer cavity 210.

Figure 2C shows the apparatus 200 after a deposition process is performed to form a dielectric material 215 (e.g., SiBCN) to sandwich the lower spacer cavity 201 to define the air gap 220. The dielectric material 215 may line the lower portion of the lower spacer cavity 210 or it may merely pinch off the upper boundary of the lower spacer cavity 210. The dielectric material 215 may be referred to as a side spacer in which an air gap is defined.

The fabrication process of the device 200 may be continued as described in fig. 1F-1J to form the upper source/drain contact structure 170 and the gate contact structure 175, as shown in fig. 2D and 2E.

The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps described above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. It is noted that various processes or structures such as "first," "second," and the like, which are used in this specification and the appended claims, are illustrative only,

The use of the terms "third" or "fourth" etc. are merely used as a quick reference to such steps/structures and do not necessarily imply that such steps/structures are performed/formed in an ordered sequence. Of course, depending on the exact claim language, an order of such processes may or may not be required. The invention is, therefore, claimed as set forth in the appended claims.