Stress relaxed buffer layer on textured silicon surface

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.

Claims

1. A method comprising: forming a textured or V-grooved surface in an upper surface of a silicon (Si) wafer, wherein the step of forming the textured or V-grooved surface on the upper surface of the Si wafer includes: forming pyramids in the upper surface of the Si wafer by etching, wherein the pyramids have a height less than 300 nm and a Si <111> surface; epitaxially growing a low-temperature seed layer on the textured surface of the Si wafer; depositing a stress relaxed buffer (SRB) layer over the low-temperature seed layer; and planarizing an upper surface of the SRB layer.

2. The method according to claim 1, wherein the planarizing comprises: planarizing the upper surface of the SRB layer with chemical-mechanical planarization (CMP).

3. The method according to claim 1, further comprising: epitaxially growing the low-temperature seed layer in trenches of the textured or V-grooved surface of the Si wafer.

4. The method according to claim 3, further comprising: epitaxially growing the low-temperature seed layer to a thickness of 10 nm to 40 nm.

5. The method according to claim 3, wherein the pyramids have a depth of less than 200 nm.

6. The method according to claim 1, wherein the low-temperature seed layer comprises germanium (Ge), indium phosphide (InP), or gallium arsenide (GaAs).

7. The method according to claim 1, further comprising: epitaxially growing the SRB layer over the low-temperature seed layer at a thickness of 200-500 nm, wherein the SRB layer includes silicon germanium (Si.sub.xGe.sub.1-x), indium gallium arsenide (InGaAs), or indium gallium arsenide phosphide (Ga.sub.xIn.sub.1-xAs.sub.yP.sub.1-y).

8. The method according to claim 1, wherein the step of forming the textured or V-grooved surface on the upper surface of the Si wafer includes: forming parallel V-grooves in the upper surface of the Si wafer.

9. A method comprising: forming a textured surface in an upper surface of a Si wafer, wherein the textured surface includes a Si <111> surface; epitaxially growing a low-temperature seed layer on the textured surface of the Si wafer, the low-temperature seed layer comprising Ge, InP, or GaAs; epitaxially growing a SRB layer over the low-temperature seed layer at a thickness of 200-300 nm, wherein the SRB layer comprises SiGe, In.sub.xGa.sub.1-xAs, or Ga.sub.xIn.sub.1-xAs.sub.yP.sub.1-y; and planarizing an upper surface of the SRB layer.

10. The method according to claim 9, further comprising: epitaxially growing the low-temperature seed layer to a thickness of 10 nm to 40 nm.

11. The method according to claim 9, wherein the planarizing comprises: planarizing the upper surface of the SRB layer with CMP.

12. The method according to claim 9, wherein the step of forming the textured surface on the upper surface of the Si wafer includes: forming pyramids or parallel V-grooves in the upper surface of the Si wafer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) 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.

(3) FIG. 2B is a scanning electron microscope image of a textured Si wafer surface.

(4) FIG. 2C is a drawing of pyramid shapes formed in surface of Si wafer.

(5) FIG. 3 is a perspective view of an Si wafer surface having V-grooved trenches formed.

DETAILED DESCRIPTION

(6) 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.

(7) The present disclosure addresses and solves the current problem of dislocation defects generated when growing semiconductor materials, such as SRB layers, on Si wafers.

(8) 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.

(9) 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.

(10) 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.

(11) 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 <111> 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.

(12) 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.

(13) 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.

(14) 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.

(15) 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.sub.xGe.sub.1-x, InGaAs, or Ga.sub.xIn.sub.1-xAs.sub.yP.sub.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).

(16) 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.

(17) 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.

(18) 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.