Abstract:
A method of forming a stress relaxed buffer layer (SRB) on a textured or grooved silicon (Si) surface and the resulting device are provided. Embodiments include forming a textured surface in an upper surface of a Si wafer; epitaxially growing a low-temperature seed layer on the textured surface of the Si wafer; depositing a SRB layer over the low-temperature seed layer; and planarizing an upper surface of the SRB layer.

Description:
TECHNICAL FIELD 
     The present disclosure relates to the manufacture of semiconductor devices. In particular, the present disclosure relates to a stress relaxed buffer (SRB) layer used in manufacturing a semiconductor device in the 14 nm, 10 nm, 7 nm, 5 nm, and 3 nm technology nodes. 
     BACKGROUND 
     With silicon (Si) wafers, epitaxial growth of different semiconductor materials having different lattice constants and thermal coefficients results in the generation of defects, such as dislocation defects which in turn lead to poor transistor performance and reliability issues. Substrates with SRB layers, including gallium arsenide (GaAs) or silicon germanium (SiGe) stepped or graded, are useful in achieving stress relaxation. However, the SRB layers are thick (e.g., ranging between 2 μm to 2.5 μm) and therefore expensive. Further, if an intermediate chemical mechanical polishing (CMP) step is used to planarize the layer and smoothen the surface roughness, there is a risk of having oxide residues on top before next epi step. Dielectric residues would than degrade the quality of the top epi layer. 
     A need therefore exists for methodology enabling the application of a thin SRB layer which achieves complete stress relaxation and locally confines defects at the bottom of trenches on a textured Si surface and the resulting device. 
     SUMMARY 
     An aspect of the present disclosure includes texturing or grooving an upper surface of a Si wafer, epitaxially growing a low-temperature seed layer on the textured or grooved surface of the Si wafer, and depositing (epi-growing) a SRB layer over the seed layer. Defects can be locally confined or trapped to within 10 nm of seed epi thickness on a textured Si surface. 
     Another aspect of the present disclosure is a device including a textured upper surface of a Si wafer, an epitaxially grown low-temperature seed layer on the textured surface of the Si wafer, and a SRB layer over the seed layer. 
     Additional aspects of the present disclosure include providing &lt;111&gt; surface within ‘V-groove’ recessed trench and growing low temperature thin epi-seed layer leads to efficient defect confinement and sufficient lattice parameter relaxation. The subsequent SRB layer is sufficiently defect-free and thin to provide good quality epi prior epi growth of the channel material. A &lt;111&gt; surface is created by means of wafer texturing or grooving. 
     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: forming a textured surface or V-grooved surface in an upper surface of a Si wafer; epitaxially growing a low-temperature seed layer on the textured surface of the Si wafer; depositing a SRB layer over the low-temperature seed layer; and planarizing an upper surface of the SRB layer. 
     Aspects of the present disclosure include planarizing the upper surface of the SRB layer with CMP. Other aspects include epitaxially growing the low-temperature seed layer in trenches of the textured surface of the Si wafer. Further aspects include epitaxially growing the low-temperature seed layer to a thickness of 10 nm to 40 nm. Additional aspects include the pyramids having a depth of less than 200 nm. Other aspects include the low-temperature seed layer including germanium (Ge), indium phosphide (InP), or gallium arsenide (GaAs). Further aspects include epi growth of the SRB layer over the low-temperature seed layer at a thickness of 200 to 300 nm, wherein the SRB layer includes silicon germanium (SiGe), indium gallium arsenide (InGaAs), or indium gallium arsenide phosphide (Ga x In 1-x As y P 1-y ). Additional aspects include forming the textured surface on the upper surface of the Si wafer including forming pyramids in the upper surface of the Si wafer by etching, wherein the pyramids have a height less than 200 nm. Another aspect includes the pyramids having a Si &lt;111&gt; surface. Additional aspects include parallel V-grooves on top of the wafer. 
     Another aspect of the present disclosure is a method including: forming a textured surface in an upper surface of a Si wafer, wherein the textured surface includes a Si &lt;111&gt; surface; epitaxially growing a low-temperature seed layer on the textured surface of the Si wafer, the low-temperature seed layer including Ge, InP, or GaAs; epi-growing a SRB layer over the low-temperature seed layer at a thickness of 200 to 300 nm, wherein the SRB layer includes SiGe, InGaAs, or Ga x In 1-x As y P 1-y ; and planarizing an upper surface of the SRB layer. 
     Aspects include epitaxially growing the low-temperature seed layer to a thickness of 10 nm to 40 nm. Further aspects include planarizing the upper surface of the SRB layer with CMP. Additional aspects include forming the textured surface on the upper surface of the Si wafer by forming pyramids or V-grooves in the upper surface of the Si wafer. 
     Another aspect of the present disclosure is a device including a Si wafer including a textured upper surface; an epitaxially grown low-temperature seed layer deposited on the textured surface of the Si wafer; and a SRB layer deposited over the low-temperature seed layer. Aspects include the epitaxially grown the low-temperature seed layer having a thickness of 10 nm to 40 nm. Further aspects include the textured surface of the Si wafer including pyramids having a Si &lt;111&gt; surface, or V-grooves having a Si &lt;111&gt; surfaces. Other aspects include the low-temperature seed layer including Ge, InP, or GaAs. Additional aspects include the SRB layer including SiGe, InGaAs, or Ga x In 1-x As y P 1-y . 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIGS. 1, 2A, 4 and 5  schematically illustrate cross sectional views of a process flow to produce a SRB layer on a textured Si wafer, in accordance with an exemplary embodiment. 
         FIG. 2B  is a scanning electron microscope image of a textured Si wafer surface. 
         FIG. 2C  is a drawing of pyramid shapes formed in surface of Si wafer. 
         FIG. 3  is a perspective view of an Si wafer surface having V-grooved trenches formed. 
     
    
    
     DETAILED DESCRIPTION 
     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 dislocation defects generated when growing semiconductor materials, such as SRB layers, on Si wafers. 
     Methodology in accordance with embodiments of the present disclosure includes forming a textured or grooved surface in an upper surface of a Si wafer; epitaxially growing a low-temperature seed layer on the textured surface of the Si wafer; depositing a SRB layer over the low-temperature seed layer; and planarizing an upper surface of the SRB layer. 
     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  FIG. 1  illustrates, in cross section, an example of Si wafer  101  having a smooth upper surface  103 . The Si wafer can have a variety of diameters from 25.4 mm to 450 mm and can be formed of a crystalline Si. The Si wafer serves as a substrate for microelectronic devices built in and over the wafer and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. 
     Adverting to  FIG. 2A , the Si wafer  101  is textured to form a plurality of pyramid shapes  201  on the upper surface  103  of the Si wafer. The pyramid shapes  201  have a peak  203  and a trench  205 . The height of each pyramid shape  201  from its peak  203  to the bottom of trench  205  is between 100 nm to 200 nm. The textured surface of the Si wafer  101  is formed on one side of the Si wafer  101  by etching processes including dry or wet etching processes or a combination of wet/dry process to form the pyramid shapes  201 . A dry etch process such as a sulfur hexafluoride based dry etch can be used to produce the irregularities on the surface of the Si wafer  101 . The entire upper surface of Si wafer  101  can be etched to provide the fine pyramid shapes  201  ranging in height between 100 to 200 nm. The pyramids  201  have a Si &lt;111&gt; surface. A wet etch process can also be used to form pyramid shapes  201  less than 200 nm in height. An aqueous solution of tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH) or sodium hydroxide (NaOH) can be used as a wet etching solution. 
     In  FIG. 2B , is a scanning electron microscope image of a textured Si wafer  101  showing the plurality of pyramid shapes  201 . In  FIG. 2C , is a drawing representing a portion of the randomly formed pyramids  201  in the image of  FIG. 2B . 
     As an alternative to the pyramid shapes  201  formed on the Si wafer  101 , a masking and orientation selective V-groove etching can be performed on the Si wafer  101 . As a result of this processing, long and parallel V-groove trenches  301  are formed across the Si wafer  101 , as illustrated in  FIG. 3 . 
     Adverting to  FIG. 4 , an epitaxially grown low-temperature seed layer  401  is formed on the textured surface of the Si wafer  101 . In particular, the low-temperature seed layer  401  is formed over the pyramid shapes  201  such that the peaks  203  and trenches  205  are covered with the epitaxially grown low-temperature seed layer  401 . The low-temperature seed layer  401  is grown to a thickness of 10 to 40 nm, for example 20 nm. The low-temperature seed layer includes typically Ge, InP, or GaAs. The temperature at which the seed layer  401  is epitaxially grown ranges between 400 and 700° C. A chemical vapor deposition (CVD) or molecular beam epitaxy (MBE) processes can be used to epitaxially grow the seed layer  401 . 
     Adverting to  FIG. 5 , a SRB layer  501  is deposited over the low-temperature seed layer  401 . The upper surface  503  of SRB layer  501  is shown planarized. Planarization can be performed with CMP. The SRB layer  501  is formed over the low-temperature seed layer  401  at a thickness of 200 to 500 nm. The SRB layer  501  includes a high mobility channel material including Ge, Si x Ge 1-x , InGaAs, or Ga x In 1-x As y P 1-y . Following the planarization of the SRB layer  501 , the silicon wafer  101  can be further processed such as adding channels. The pyramids  201  can be detected by cross-sectional transmission electron microscopy (X-TEM). 
     The embodiments of the present disclosure can achieve several technical effects, such as a quick formation of a fully relaxed SRB layer. The present invention allows for the formation of the SRB layer with a low cost process. 
     Devices formed in accordance with embodiments of the present disclosure enjoy utility in various industrial applications, e.g., 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. The present disclosure therefore enjoys industrial applicability in the manufacture of any of various types of highly integrated semiconductor devices using Si wafers having a thin SRB layer which achieves complete stress relaxation and locally confines defects at the bottom of trenches on a textured Si surface. The present disclosure is particularly applicable to the 14 nm technology node 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.