Patent Application
20160126336
The present disclosure relates to process flows for contact formation. More particularly, the present disclosure relates to gate contacts for replacement metal gate (RMG) processing.
Although in many structures, source/drain contacts (CA) and gate contacts (CB) are separated, in some circuits, the gate and source/drain need to be connected, thereby requiring a merged CA/CB contact.
A need therefore exists for methodology enabling formation of a CA/CB construct with an increased gate contact area and the resulting device.
An aspect of the present disclosure is a merged CA/CB construct contacting one side of a RMG.
Another aspect of the present disclosure is a merged CA/CB construct contacting both sides of a RMG.
Additional aspects and other features of the present disclosure will be set forth in the description which follows and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the present disclosure. The advantages of the present disclosure may be realized and obtained as particularly pointed out in the appended claims.
According to the present disclosure, some technical effects may be achieved in part by a method including: providing a replacement metal gate (RMG) between first and second sidewall spacers surrounded by an insulator on a substrate, the RMG having a dielectric layer directly on the first and second sidewall spacers and having metal on the dielectric layer; providing an oxide layer over the insulator, the first and second sidewall spacers, and the RMG; forming a source/drain contact hole through the oxide layer and the insulator, adjacent to the first sidewall spacer; forming a gate contact hole through the oxide layer over the source/drain contact hole and extending to the metal of the RMG; enlarging the source/drain contact hole to the metal of the RMG; and filling the enlarged source/drain contact hole and gate contact hole with metal.
Aspects of the present disclosure include the enlarging of the source/drain contact hole including: removing the insulator between the source/drain contact hole and the first sidewall spacer; and removing the first sidewall spacer and the dielectric layer on the first sidewall spacer. Further aspects include removing the insulator between the source/drain contact hole and the first sidewall spacer concurrently with forming the gate contact hole. Other aspects include removing the insulator between the source/drain contact hole and the first sidewall spacer and forming the gate contact hole by reactive ion etching (RIE). Another aspect includes removing the first sidewall spacer and dielectric layer by a second RIE. Additional aspects include the dielectric layer including a high-K (HK) dielectric. Further aspects include the metal of the RMG including at least one work function metal directly on the dielectric layer and tungsten filling a remainder of the RMG, the method further including removing the at least one work function metal on a first sidewall spacer side of the tungsten concurrently with the first sidewall spacer and the dielectric layer. Additional aspects include forming the gate contact hole extending over a portion of the insulator surrounding the second sidewall spacer; removing the portion of the insulator under the gate contact hole and surrounding the second sidewall spacer concurrently with forming the gate contact hole; and removing the second sidewall spacer, the dielectric layer on the second sidewall spacer, and the at least one work function metal on both sides of the tungsten concurrently with the first sidewall spacer and the dielectric layer on the first sidewall spacer.
Another aspect of the present disclosure is a device including: a replacement metal gate having a metal; and a source/drain and gate contact construct including: a first portion directly contacting a sidewall of the metal, and a second portion over the first portion and the metal.
Aspects include the metal including at least one work function metal on opposite sides of a metal fill, and the first portion directly contacting the at least one work function metal. Further aspects include the metal including tungsten, and the first portion directly contacting the tungsten. Additional aspects include the source/drain and gate contact construct including a third portion directly contacting a second sidewall of the tungsten; and the second portion extending over the third portion. Other aspects include the source/drain and gate contact construct including tungsten.
Another aspect of the present disclosure is a method including: providing a replacement metal gate (RMG) between first and second sidewall spacers surrounded by an insulator on a substrate, the RMG having first and second portions of a dielectric layer directly on the first and second sidewall spacers, respectively, and having metal filling a space between the first and second portions of the dielectric layer; providing an oxide layer over the insulator, the first and second sidewall spacers, and the RMG; forming a source/drain contact hole through the oxide layer and the insulator, adjacent to the first sidewall spacer; performing a first reactive ion etch (RIE) to form a gate contact hole through the oxide layer over the source/drain contact hole and extending to the metal of the RMG; enlarging the source/drain contact hole to the first sidewall spacer concurrently with forming the gate contact hole; performing a second RIE to remove the first sidewall spacer and first portion of the dielectric layer to expose the metal, further enlarging the source/drain contact hole; and filling the further enlarged source/drain contact hole and gate contact hole with a contact metal.
Aspects include the dielectric layer including a high-K (HK) dielectric. Further aspects include the metal of the RMG including at least one work function metal directly on the first portion of the dielectric layer and tungsten filling a remainder of the RMG, and the second RIE exposing the at least one work function metal. Further aspects include the metal of the RMG including at least one work function metal directly on each of the first and second portions of the dielectric layer and tungsten filling a remainder of the RMG, the method further including removing the at least one work function metal on the first portion of the dielectric layer concurrently with the first sidewall spacer and the first portion of the dielectric layer. Additional aspects include forming the gate contact hole extending over the insulator surrounding the second sidewall spacer; removing the insulator under the gate contact hole and surrounding the second sidewall spacer concurrently with forming the gate contact hole; and removing the second sidewall spacer, the second portion of the dielectric layer, and the at least one work function metal on the second portion of the dielectric layer concurrently with the first sidewall spacer and the first portion of the dielectric layer. Further aspects include forming the source/drain contact down to a source/drain region, and forming a silicide on the source/drain region prior to filling the enlarged source/drain contact hole. Another aspect includes the contact metal including tungsten.
Additional aspects and technical effects of the present disclosure will become readily apparent to those skilled in the art from the following detailed description wherein embodiments of the present disclosure are described simply by way of illustration of the best mode contemplated to carry out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawing and in which like reference numerals refer to similar elements and in which:
In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments. It should be apparent, however, that exemplary embodiments may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring exemplary embodiments. In addition, unless otherwise indicated, all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.”
The present disclosure addresses and solves the current problem of low process margin and unreliable contact formation attendant upon forming conventional CA/CB contacts. In accordance with embodiments of the present disclosure, a merged CA/CB construct includes an upper portion along an upper surface of the gate and a lower portion in contact with at least one vertical surface of either a work function metal or the metal fill of the gate.
Methodology in accordance with embodiments of the present disclosure includes providing a replacement metal gate (RMG) between first and second sidewall spacers surrounded by an insulator on a substrate, the RMG having a dielectric layer directly on the first and second sidewall spacers and having metal on the dielectric layer. An oxide layer is provided over the insulator, the first and second sidewall spacers, and the RMG. A source/drain contact hole through the oxide layer and the insulator, is formed adjacent to the first sidewall spacer, and a gate contact hole is formed through the oxide layer over the source/drain contact hole extending to the metal of the RMG. The source/drain contact hole is extended to the metal of the RMG, and the enlarged source/drain contact hole and gate contact hole is filled with metal.
Still other aspects, features, and technical effects will be readily apparent to those skilled in this art from the following detailed description, wherein preferred embodiments are shown and described, simply by way of illustration of the best mode contemplated. The disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
Adverting to
As shown in
Adverting to
As illustrated in
Adverting to
As illustrated in
Adverting to
Adverting to
Adverting to
Adverting to
As illustrated in
The embodiments of the present disclosure can achieve several technical effects, including an increased contact area, which is especially beneficial for FinFETs and which reduces contact resistance, an increased misalignment process margin by 20 to 30 nm, more reliable tungsten filling, due to a smaller aspect ratio, and improved open/short yield, all of which contribute to higher yield and improved device performance (e.g., a smaller RC time constant). The present disclosure enjoys industrial applicability associated with the designing and manufacturing of any of various types of highly integrated semiconductor devices used in microprocessors, smart phones, mobile phones, cellular handsets, set-top boxes, DVD recorders and players, automotive navigation, printers and peripherals, networking and telecom equipment, gaming systems, and digital cameras, particularly for 14 nm technology nodes and beyond.
In the preceding description, the present disclosure is described with reference to specifically exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure, as set forth in the claims. The specification and drawings are, accordingly, to be regarded as illustrative and not as restrictive. It is understood that the present disclosure is capable of using various other combinations and embodiments and is capable of any changes or modifications within the scope of the inventive concept as expressed herein.
