DE102006058820A1 - Method of making SGOI and GeOI semiconductor structures - Google Patents

Abstract

The invention relates to a method for producing a SGOI or a GeOI semiconductor structure, comprising a) providing a substrate of monocrystalline silicon; b) depositing a germanium layer on the substrate comprising at least one atomic amount of germanium; c) implanting oxygen ions into the Ge-coated substrate, wherein the implantation energy is greater than or equal to 1 eV and less than or equal to 1 keV; d) thermal treatment of the oxygen-implanted substrate at a temperature greater than or equal to 600 ° C and less than 938 ° C. The invention also relates to a method for producing a SGOI semiconductor structure in which a cover layer of monocrystalline silicon is deposited after the oxygen implantation and the thermal treatment of the oxygen-implanted substrate at temperatures of greater than or equal to 900 ° C and less than or equal to 1300 ° C.

Description

The The invention relates to a method for the production of SGOI and GeOI semiconductor structures.

State of the art

in the State of the art SOI ("Silicon on insulator ") - structures usually either by the so-called SIMOX ("separation by ion implantation of Oxygen ") - process or produced by layer transfer method.

At the SIMOX process is high in a silicon substrate oxygen Doses implanted, this then at high temperatures (> 1200 ° C) thermally treated and oxidized to a buried oxide layer in the silicon substrate to create.

In the layer transfer process, a release layer is produced just below the surface of a silicon wafer (the so-called donor disk). The release layer is, for example, a layer with cavities, which is usually produced by implanting hydrogen into this region. The donor sheet prepared in this way is then bonded to a second disk, the carrier disk, and then the donor disk is split along the release layer, thereby transferring one or more layers of the donor disk to the carrier disk using layer transfer are for example in EP 533551 A1 . WO 98/52216 A1 or WO 03/003430 A2 described.

SIMOX and layer transfer processes are also suitable for the production of SGOI ("silicon / germanium on insulator") and / or GeOI ("germanium on insulator") structures: US 2005/0153487 A1 discloses a method of making a SGOI substrate comprising two oxygen (high-dose & low-dose) implantations into a silicon substrate at implant energies of 100-220 keV, then depositing a 10-500 nm thick germanium-containing layer (eg a silicon germanium (SiGe) layer) on the substrate and subsequent multi-step thermal treatment of the substrate.

In Applied Physics Letters Vol. 79, Number 12, p. 1798-1800, T. Tezuka et al. it is reported that a SiGe layer by CVD ("Chemical Vapor Deposition") to be deposited on a SIMOX substrate, then subjected to a thermal treatment in an oxygen atmosphere, whereby the substrate is oxidized, the SiGe layer is thus downwardly and upwardly by SiO ₂ layers, which represent a diffusion barrier for germanium atoms, whereby within the condensed SiGe layer is a homogeneous germanium profile is generated. After removal of the upper SiO ₂ layer results in a dislocation-free SGOI substrate with a homogeneous germanium profile.

In US2005 / 0039100 A1 describes a method for generating SGOI and GeOI structures in which a GeOl structure is transferred to a carrier wafer by implanting hydrogen ions of an energy of 100 keV into an oxidized, germanium-containing donor wafer, bonding to carrier wafer and subsequent thermal treatment. The GeOl disc produced thereby comprises a germanium layer, a buried SiO ₂ layer, wherein a silicon separation layer is located between the SiO ₂ layer and the Ge layer.

The Methods known in the art are due to use of high-energy implantation technologies (implantation energies Oxygen, hydrogen of 100-220 keV) as well as for additional Process steps, such as a bonding step in the layer transfer process or because of very high process temperatures relatively expensive and expensive.

task

Therefore The object of the invention was a much cheaper To provide methods of making SGOI and GeOI semiconductor structures.

description

• a) Bereitstellen eines Substrats aus monokristallinem Silicium;
• b) Abscheiden einer Germaniumschicht auf dem Substrat, die aus wenigstens einer Atomlage Germanium besteht; c) Implantation von Sauerstoffionen in das mit einer Germaniumschicht versehene Substrat, wobei die Implantationsenergie größer oder gleich 1eV und kleiner oder gleich 1keV beträgt; d) thermische Behandlung des sauerstoffimplantierten Substrats bei einer Temperatur von größer oder gleich 600°C und kleiner als 938°C.

The object of the invention is achieved by a method for producing SGOI and GeOI semiconductor structures, comprising

• a) providing a substrate of monocrystalline silicon;
• b) depositing a germanium layer on the substrate consisting of at least one atomic layer of germanium; c) implantation of oxygen ions in the substrate provided with a germanium layer, wherein the implantation energy is greater than or equal to 1eV and less than or equal to 1keV; d) thermal treatment of the oxygen-implanted substrate at a temperature greater than or equal to 600 ° C and less than 938 ° C.

First, will in step a) provided a substrate of monocrystalline silicon.

This is preferably a polished silicon wafer, which in the prior art by pulling a silicon single crystal, separating a disc of this single crystal, mechanical processing steps such as grinding or lapping, cleaning and etching steps and smoothing of Slice surface by polishing, is produced.

On this substrate will follow in step b) deposited a germanium layer. This is preferably done by a chemical vapor deposition (CVD) according to state of the technique. The deposited germanium layer comprises at least an atomic layer germanium.

The Germanium layer can be deposited either pseudomorphically or as a relaxed layer.

Around to obtain a pseudomorphic layer, depending on the selected deposition temperature the respective critical thickness falls below that of the deposition temperature become.

The literature reports that the critical thickness for pseudomorphic growth of germanium on silicon is d <d _crit , with d ~ 2-4 nm. ( JW Matthews, AE Blakeslee in J. Crystal Growth, 27, (1974) 118 )

Preferably For example, the thickness of the deposited germanium layer is smaller than that critical thickness for pseudomorphic growth of germanium on silicon. This will avoided that relaxation processes lead to dislocations in the Ge layer.

It can but also thicker layers are deposited. It happens to an at least partial relaxation of the germanium layer.

In Step c) oxygen ions are in the with a germanium layer implanted substrate implanted. The implantation energy is 1eV-1keV.

Preferably is the implantation energy 1eV-500eV.

The implantation dose is preferably greater than or equal to 1 × 10 ¹⁴ cm ^-2 and less than or equal to 1 × 10 ¹⁷ cm ^-2 . It is preferably chosen depending on the desired final oxide thickness after thermal treatment.

there The oxygen ions are close to the surface and preferably only to a depth of greater or less implanted equal to 10 nm and less than or equal to 30 nm below the substrate surface.

In addition will the implantation direction preferably chosen so that the interaction of the Oxygen with the germanium lattice is as low as possible. This is when implanted along the <110> direction. ( "Channeling Effect").

The In addition, precise implantation conditions are preferred chosen so that is in the over no germanium layer already deposited on the silicon substrate Implantation-related defects show. This is also the effect used germanium with oxygen at low implantation energies elastically interacts.

So is an extra Heating the silicon substrate at temperatures of 200 ° C or less during the Implantation is preferred to the formation of implantation defects even stronger to suppress.

in the Following the oxygen implantation is preferably a thin silicon layer ("capping layer") on the germanium layer deposited. This is preferably done by chemical vapor deposition (CVD).

The Thickness of the deposited silicon layer is preferably greater than or equal to equal to 1 nm and less than or equal to 100 nm, most preferably bigger or equal to 5 nm and less than or equal to 50 nm.

These Cover layer has the function, the thin germanium layer before or while to protect the subsequent thermal treatment, facilitates handling the silicon wafer and allows the choice of a wider process window in the subsequent thermal Treatment.

Farther is provided with a germanium layer and oxygen-implanted Substrate in step d) of a thermal treatment at a temperature from bigger or equal to 600 ° C and less than 938 ° C subjected.

The Treatment temperature is preferably greater than or equal to 650 ° C and less or equal to 800 ° C.

The Duration of the thermal treatment is preferably less than 1 hour, typically at 10-30 Minutes.

By This thermal treatment diffuses the oxygen up to the Germanium interface. There is the oxygen diffusion stopped because the germanium layer is a diffusion barrier.

By phase transformation, an SiO ₂ oxidation zone forms directly below the preferably pseudomorphic Ge layer.

The thickness of the oxidation zone (end oxide thickness) is preferably 30 nm or less ger, more preferably at 10 nm or less.

The Germanium layer remains structurally preserved as germanium oxidize much worse than silicon, and also a very low diffusivity having.

To the thermal treatment in step d), if previously Silicon cover layer was deposited, these preferably again away. This creates a GeOI disk.

Becomes does not remove the silicon overcoat, which is also preferred is, creates a SGOI disc.

Has been before the thermal treatment in d) no silicon covering layer is deposited, performs the described Method also to a GeOI disc.

The The object of the invention is also achieved by a method for Production of an SGOI semiconductor structure, comprising a) providing a Substrate of monocrystalline silicon; b) depositing a germanium layer on the substrate consisting of at least one atomic layer of germanium; c) implantation of oxygen ions in the with a germanium layer provided substrate, wherein the implantation energy greater or is equal to 1 eV and less than or equal to 1 keV; d) depositing a cover layer of monocrystalline silicon on the germanium layer; e) thermal Treatment of the oxygen-implanted substrate at temperatures of bigger or equal to 900 ° C and less than or equal to 1300 ° C.

This Method differs from the method described above essentially by the deposition of a silicon overcoat on the Substrates in step d) and by a modified thermal treatment in step e).

In This case happens the thermal treatment such that the germanium layer during the thermal treatment, preferably towards the end of the thermal Treatment, completely dissolves and finally forming a SGOI disk.

First, will in step a) provided a substrate of monocrystalline silicon.

On this substrate will follow in step b) deposited a germanium layer. This is preferably done by a chemical vapor deposition (CVD) according to state of the technique. The deposited germanium layer comprises at least an atomic layer germanium.

The Germanium layer can be deposited either pseudomorphically or as a relaxed layer.

Around to obtain a pseudomorphic layer, depending on the selected deposition temperature the respective critical thickness falls below that of the deposition temperature become.

Preferably For example, the thickness of the deposited germanium layer is smaller than that critical thickness for pseudomorphic growth of germanium on silicon.

It can but also thicker layers are deposited. It happens to an at least partial relaxation of the germanium layer.

In Step c) oxygen ions are in the with a germanium layer implanted substrate implanted. The implantation energy is 1eV-1keV.

Preferably is the implantation energy 1eV-500eV.

The implantation dose is preferably greater than or equal to 1 × 10 ¹⁹ cm ^-2 and less than or equal to 1 × 10 ¹⁷ cm ^-2 . It is preferably chosen depending on the desired final oxide thickness after thermal treatment.

there The oxygen ions are close to the surface and preferably only to a depth of greater or less implanted equal to 10 nm and less than or equal to 30 nm below the substrate surface.

Subsequently, will in step d) a silicon layer ("cover layer") is deposited on the germanium layer. This is preferably done by chemical vapor deposition (CVD).

The Thickness of the deposited silicon layer is preferably greater than or equal to equal to 1 nm and less than or equal to 100 nm, most preferably bigger or equal to 5 nm and less than or equal to 50 nm.

In e) a thermal treatment is carried out with a germanium layer and a silicon capped, oxygen-implanted Substrate at temperatures of 900-1300 ° C.

Preferably the thermal treatment is carried out by a temperature profile, at which the treatment temperature towards the end of the thermal Treatment of the melting temperature of germanium (938 ° C) approximates or but this clearly exceeds, So up to a temperature of 1300 ° C, and thereby to a accelerated outdiffusion of germanium leads.

Preferably In this thermal treatment, the temperature becomes smaller or equal to 100 ° C per minute, most preferably at 10-50 ° C per minute ("anneal ramp").

Here, too, an SiO ₂ oxidation zone forms below the germanium layer first by means of phase transformation. The oxygen diffusion is also stopped in this case at the interface germanium / silicon.

In summary essentially only require the described methods a relatively simple epitaxy step (deposition of germanium or deposition of a silicon cover layer) and a low-energy Implantation step (1eV-1keV) and are thus considerably cheaper and thus more economical than previously for the generation of GeOI or SGOI structures used technologies.

On the SiGe or Ge layers of the SGOI and / or GeOI structures become preferably epitaxial layers (e.g., epitaxial layers from SiGe and / or Ge, to increase the respective layer thicknesses). such SiGe or Ge surfaces are preferably used as monocrystalline templates for further epitaxial growth e.g. of III-V semiconductors such as GaAs or GaN.

example

In a first process step, a defect-free isomorphous germanium layer is deposited on a monocrystalline silicon wafer in a CVD reactor. For this purpose, a silicon wafer cleaned by means of hydrofluoric acid is charged into the reactor, heated in a hydrogen atmosphere to a temperature of T = 850 ° C. (low-temp bake), then cooled to a process temperature of 400 ° C. and finally a germanium layer of 4 nm thickness deposited by means of the deposition gas GeH ₄ .

In a second process step, an oxygen implantation takes place. For this purpose, the Ge / Si disk is loaded into a plasma chamber, then oxygen is implanted in a near-surface layer at an internal energy of 100 eV and a dose of 1.5 × 10 ¹⁶ cm ^-2 .

In this case, an oxygen profile is set in which oxygen is implanted to a depth of about 10 nm below the disk surface. The oxygen concentration is 5 × 10 ¹⁶ cm ^-3 in the oxygen-implanted layer.

In the next process step, a silicon layer is deposited. In this case, the oxygen-implanted Ge / Si disk is loaded into a CVD system and a silicon layer having a thickness of 50 nm is deposited at a temperature of T = 500 ° C. and SiH ₄ as a silicon source.

in the next Step is followed by a thermal treatment in a tempering furnace a temperature of 850 ° C for the Duration of 2 min.

Subsequently, will removed the silicon layer in a wet chemical etching process. It arises a GeOI disk.

alternative the thermal treatment takes place in a tempering furnace for the duration of 10 minutes and an anneal ramp of 900 ° C to 1100 ° C. This corresponds to the modified one thermal treatment, in which the germanium layer against Preferably, dissolve completely at the end of the treatment. The silicon topcoat will not be removed in this case. This creates a SGOI disc.

The Thickness of the oxide was measured by ellipsometry and was 10 nm ± 1.5 nm. The breakdown field strength of the oxide was determined by electrical testing and was 8 MV / cm.

characters

The invention will now be described with reference to the 1 to 3 be illustrated.

1 schematically shows the sequence of a method for producing a SGOI or a GeOI disc.

2 schematically shows the sequence of a method for producing a GeQI disk.

3 schematically shows the sequence of a method for producing a SGOI disc by means of modified thermal treatment.

1a) -F) shows schematically the procedure of a method for the production of SGOI and GeQI disks. First, in step (a), a substrate 1 provided. On substrate 1 becomes in step b) a germanium layer 2 deposited. In step c), oxygen ions become a region 3 from substrate 1 implanted. In step d) is on germanium layer 2 a silicon capping layer 4 deposited. In e), a thermal treatment takes place, thereby forming an oxide layer 3a within substrate 1 and it creates a SGOI disc. In optional step f) the cover layer becomes 4 removed and it results in a GeOI disc.

2a) -D) shows the sequence of a method for producing a GeOI disc. In step a) becomes substrate 1 provided. In b) becomes a Germa niumschicht 2 on substrate 1 deposited. In c), oxygen ions become a region 3 from substrate 1 implanted. In d), a thermal treatment takes place, it forms an oxide layer 3a within substrate 1 and it creates a GeOI disk.

3a) -E) shows the sequence of a method for producing a SGOI disc by means of modified thermal treatment. In a) becomes substrate 1 provided. In b) is on substrate 1 a germanium layer 2 deposited. In c), oxygen ions become a region 3 from substrate 1 implanted. In d) is on germanium layer 2 a silicon capping layer 4 deposited. In e), a thermal treatment takes place in an anneal ramp of 900-1300 ° C, thereby forming an oxide layer 3a within substrate 1 , a SiGe layer 5 arising from the original germanium layer 2 and a part of topcoat 4 forms. The remaining part 4a the topcoat is not removed. This creates a SGOI disc.

Claims (18)

Method for producing an SGOI semiconductor structure, comprising a) providing a substrate of monocrystalline silicon; b) depositing a germanium layer on the substrate, which comprises at least one atomic layer of germanium; c) implantation of oxygen ions in the substrate, with the implantation energy bigger or is equal to 1 eV and less than or equal to 1 keV; d) depositing a cover layer of monocrystalline silicon on the germanium layer; e) thermal Treatment of the oxygen-implanted substrate at temperatures of bigger or equal to 900 ° C and less than or equal to 1300 ° C. The method of claim 1, wherein the germanium layer pseudomorphically deposited. The method of claim 1, wherein the germanium layer is deposited as a relaxed layer. The method of claim 2, wherein the thickness of the deposited Germanium layer smaller than the critical thickness for pseudomorphic Growth of germanium on silicon is. The method of claim 4, wherein the deposited Germanium layer has a thickness of 1-4 nm. The method of claim 1, wherein in step c) oxygen ions with an implantation energy greater than or equal to 1 eV and smaller or equal to 500 eV implanted. The method of claim 1, wherein the oxygen implantation dose in step c) is greater than or equal to 1 × 10 ¹⁴ cm ^-2 and less than or equal to 1 × 10 ¹⁷ cm ^-2 . The method of claim 7, wherein the oxygen ions in step c) near the surface to a depth of greater or less implanted equal to 10 nm and less than or equal to 30 nm below the substrate surface become. Process for the preparation of a SGOI or a GeOI semiconductor structure, comprising a) providing a substrate of monocrystalline silicon; b) depositing a germanium layer on the substrate, which comprises at least one atomic layer of germanium; c) implantation of oxygen ions into the Ge-coated substrate, where the implantation energy is greater than or equal to 1 eV and smaller or equal to 1 keV; d) thermal treatment of the oxygen-implanted substrate in a Temperature of greater or equal to 600 ° C and less than 938 ° C. The method of claim 9, wherein the germanium layer pseudomorphically deposited. The method of claim 9, wherein the germanium layer is deposited as a relaxed layer. The method of claim 9, wherein the thickness of the deposited Germanium layer smaller than the critical thickness for pseudomorphic Growth of germanium on silicon is. The method of claim 9, wherein the deposited Germanium layer has a thickness of 1-4 nm. The method of claim 9, wherein in step c) oxygen ions with an implantation energy greater than or equal to 1 eV and smaller or equal to 500 eV implanted. The method of claim 9, wherein the oxygen implantation dose in step c) is greater than or equal to 1 × 10 ¹⁴ cm ^-2 and less than or equal to 1 × 10 ¹⁷ cm ^-2 . The method of claim 9, wherein the oxygen ions close to the surface to a depth of greater or less implanted equal to 10 nm and less than or equal to 30 nm below the substrate surface become. The method of claim 9, wherein after oxygen implantation according to c) and before the thermal treatment according to d) a silicon covering layer is deposited on the germanium layer. Method according to claim 17, characterized in that that the silicon covering layer after the thermal treatment in Step d) is removed again.