JP4853990B2 - Method for producing strained crystal layer on insulator, semiconductor structure by said method and manufactured semiconductor structure - Google Patents

Description

  The present invention relates to a method of manufacturing a strained crystal layer on an insulator, a semiconductor structure for manufacturing a strained crystal layer on an insulator, and a semiconductor structure manufactured thereby.

  A strained thin semiconductor layer such as a silicon layer has advantageous electronic properties and hole mobility properties. Therefore, such layers are of great interest in almost every field of microelectronics, since the use of such layers can lead to high performance devices with high speed and low power consumption. A strained semiconductor layer can be used even more effectively if it is transferred over the insulator layer, resulting in a structure like SOI (Silicon On Insulator), which Advantages are generally known in microelectronics and micromechanics.

  Cheng et al. Published the paper “SiGe-on-Insulator (SGOI): Substrate Preparation and MOSFET Fabrication for Electron Mobility Evaluation” in 2001 IEEE International SOI Conference. In this method, a graded SiGe layer was grown on a single crystal silicon donor wafer. During SiGe growth, the germanium content of SiGe was gradually increased until the germanium percentage reached about 25%. In the above percentages, a relaxed SiGe layer was grown on the graded SiGe layer. Further, hydrogen ions were implanted into the relaxed SiGe layer, thereby forming a previously weakened surface portion in the relaxed SiGe layer. Thereafter, the implanted structure was bonded to an oxidized silicon wafer. After annealing, the bonded structure was split into two parts along the pre-weakened face part, resulting in an on-insulator SiGe structure and a residual structure. Subsequently, a strained silicon layer was grown on the SiGe layer, resulting in a Si-on-SiGe-on-insulator (Si-on-insulator) structure.

  The method structure described above has the disadvantage that the strain of the strained silicon layer on the SiGe layer cannot be increased to a commercially important value. This is because the germanium content of the SiGe layer is limited, and the content is reduced to 25% without the risk of forming a high dislocation density in the SiGe layer that significantly affects the electronic properties of the strained silicon layer. It cannot be increased.

  It is an object of the present invention to provide a semiconductor structure and a simple method for manufacturing a semiconductor structure comprising a high quality crystal and a crystal semiconductor layer that is heavily distorted on an insulator.

  The object is solved by a method for producing a strained crystal layer on an insulator, the method comprising providing a semiconductor donor substrate comprising germanium and / or an A (III) -B (V) semiconductor; Providing at least one first crystal epitaxial layer (the content of germanium and / or A (III) -B (V) semiconductor in the buffer layer of the first layer is proportional during the first step) Providing at least one insulator layer in the second step (the first layer is provided between the substrate and the insulator layer), and in the third step Dividing the first layer, and providing at least one second crystal epitaxial layer on the divided first layer in a fourth step.

  The method of the present invention can produce a semiconductor structure in which germanium and / or A (III) -B (V) semiconductor content decreases in the direction from the substrate to the second layer. Thus, a very high content of germanium and / or A (III) -B (V) semiconductor can be achieved in the first layer, resulting in a large strain in the second layer. The increase in germanium and / or A (III) -B (V) semiconductor allows at least a portion of the first layer to grow with a low defect density, resulting in high quality crystals in the second layer. It is. The large strained high quality second layer can be easily transferred to the insulator layer by the method of the present invention, resulting in the advantages of SOI structure and the very good electronic properties of the strained crystal layer. Resulting in a semiconductor structure.

  According to a further embodiment of the invention, the first layer is a single crystal germanium wafer, a single crystal A (III) -B (V) semiconductor wafer, an epitaxial germanium layer or an epitaxial layer in the first step. It is provided on the A (III) -B (V) semiconductor layer. On the substrate, the first layer can be grown with a high germanium content and high quality crystals. Germanium wafers and / or A (III) -B (V) semiconductor wafers are stable substrates that can successfully handle strained crystal layers on insulators in the manufacturing process.

  In an advantageous embodiment of the invention, the content of germanium and / or A (III) -B (V) semiconductor in the buffer layer is about 40% -80%, preferably in the first step Reduced to about 50% -80% or about 60% -80% germanium. Such a large amount of germanium and / or A (III) -B (V) semiconductor increases the strain of the second layer.

  In a preferred embodiment of the present invention, the silicon content of the buffer layer is about 30% to 60%, preferably about 20% to 50%, or about 20% to 40% in the first step. Increased to silicon. The proportional increase in silicon provides a good relaxation of the buffer layer, in particular the GeSi layer, in the first step.

  In another preferred embodiment of the invention, the second layer is grown to a thickness of less than 50 nm. The thickness of the layer is less than the limit thickness so as to prevent the thermodynamic instability of the layer. In the thin layer of the present invention, the strain can be increased effectively.

The object is further solved by a semiconductor structure for producing a strained crystal layer on an insulator, the structure comprising a semiconductor donor substrate of a first material comprising germanium and / or an A (III) -B (V) semiconductor; At least one crystal epitaxial layer and at least one insulator layer are included. Here, the at least one crystal epitaxial layer is an intermediate layer between the donor substrate and the insulator layer, and the at least one crystal epitaxial layer is germanium and / or the A (III) -B (V). A buffer layer having a composition containing a semiconductor is included, and the content of germanium and / or the A (III) -B (V) semiconductor is reduced in the direction from the substrate to the insulator layer.

  The structure of the present invention is an intermediate product for producing a strained crystal layer on an insulator layer. Due to the onset of germanium and / or A (III) -B (V) semiconductor in the crystal epitaxial layer, the crystal epitaxial layer has a low defect density and is also low in germanium and / or A (III) -B (V) semiconductor. It can be grown in a high content state, and the high content is the basis for good growth of a highly distorted high quality additional crystal layer, for example on a crystal epitaxial layer of the structure of the invention.

  In a preferred variant of the invention, the donor substrate is a single crystal germanium wafer, a single crystal A (III) -B (V) semiconductor wafer, an epitaxial germanium layer or an epitaxial A (III) -B (V) semiconductor layer. is there. The wafer contains a large amount of germanium and / or A (III) -B (V) semiconductor, as well as an epitaxial layer, so that germanium and / or A (III) -B (V) is high on the substrate. The semiconductor crystal epitaxial layer grows well, and in this case, the defect density of the crystal epitaxial layer is low.

  In a preferred form of the invention, the content of germanium and / or A (III) -B (V) semiconductor in the crystal epitaxial layer is about 40% to 80%, desirably about 50% to 80% or about 60%. % To 80%. A germanium and / or A (III) -B (V) semiconductor with a percentage of about 40% to 80% allows the strained crystal layer to grow well on the crystal epitaxial layer, whereas the upper crystal layer A percentage of about 50% to 80% is more advantageous for greater strain, and a range of about 60% to 80% germanium is most advantageous for providing very large strain on the crystalline layer above the crystalline epitaxial layer. It is a range.

  According to an advantageous embodiment of the invention, the silicon content of the crystal epitaxial layer is increased in the direction from the substrate to the insulator layer. The proportional increase in silicon makes the lattice better adaptable, which leads to a reduction in the defect density of the crystal epitaxial layer.

  In another desirable embodiment of the invention, the silicon content is increased to a ratio of about 20-60%, desirably about 20% -50% or about 20% -40% silicon. A percentage of silicon of about 20% to 60% results in a decrease in the defect density of the crystal epitaxial layer and a well-matched crystal epitaxial layer such as a silicon layer, on the other hand, very much above the crystal layer such as a silicon layer. A percentage of 20% to 50% silicon is more favorable for the high crystallinity of the crystal epitaxial layer that provides good properties, and forms a good basis for a high quality strained crystal layer on the crystal epitaxial layer A percentage of 20% to 40% silicon is the most convenient range to provide a high quality crystalline epitaxial layer.

  In yet another desirable form of the invention, the first layer and / or the second layer comprises carbon. Desirably, a carbon concentration of a few percent carbon or even less than 1% carbon provides excellent stability dopants and high levels of strain in the first and / or second layers.

The object of the invention is further solved by a semiconductor structure, which comprises a semiconductor base substrate, at least one insulator layer and at least one first crystal epitaxial layer. Here, the insulator layer is an intermediate layer between the base substrate and the first layer, and the first layer includes germanium and / or the A (III) -B (V) semiconductor. The content of germanium and / or the A (III) -B (V) semiconductor is reduced in the direction from the second layer to the insulator layer .

  Due to the reduction of germanium and / or A (III) -B (V) semiconductor in the buffer layer, the defect density of at least a portion of the first layer is very low, so that further over the first layer The layer results in high quality crystals.

  In another preferred embodiment of the invention, the structure further comprises at least one distorted second crystalline epitaxial layer. Here, the first layer is an intermediate layer between the insulator layer and the second layer. The structure of the present invention combines both the advantages of the SOI structure and the good conductivity characteristics of the strained crystal layer. Since the content of germanium and / or A (III) -B (V) semiconductor in the first layer can be adjusted to a very high content, the strained layer can have a very large strain.

  In a further preferred variant of the invention, the content of germanium and / or A (III) -B (V) semiconductor in the buffer layer is about 40% to 80%, preferably about 50% to 80%, or Reduced to about 60-80% germanium. The content of germanium and / or A (III) -B (V) semiconductor of 40% to 80% is relatively large, and the crystal epitaxial layer such as a silicon layer on the first layer is greatly strained by the content. In contrast, a percentage of about 50% to 80% is more convenient to achieve large strain results in the crystalline epitaxial layer on top of the first layer, such as a silicon layer on the first layer. A percentage of about 60% to 80% is the most convenient range to produce very large strain results in the epitaxial layer.

In another embodiment of the invention, the silicon content of the buffer layer is increased in the direction from the second layer to the insulator layer . Due to the increase in silicon, the lattice of the buffer layer is well adapted in the direction towards the second layer, so that at least part of the first layer has good quality for the high quality crystallinity of the second layer. The high quality crystallinity that is the base is brought about.

  In yet another desirable form of the invention, the silicon content is increased to a ratio of about 20% to 60%, desirably about 20% to 50% or about 20% to 40% silicon. A strained silicon layer grows well on the first layer with an amount of silicon of about 20% to 60%. In contrast, a percentage of 20% to 50% is more convenient to provide a more heavily distorted silicon layer on the first layer, and to provide a highly distorted silicon layer on the first layer. A percentage of 20% to 40% is the most convenient range.

  In a further advantageous form of the invention, the strained layer is less than 50 nm thick. This layer thickness provides good thermodynamic stability for the second layer, so that the strain can be easily increased in the thin layer.

  In a further advantageous embodiment of the invention, the first layer and / or the second layer comprises carbon. The carbon content makes the first layer and / or the second layer more stable and exhibits a better level of strain.

  The object of the present invention is further solved by a method of producing a strained crystal layer on an insulator, the method comprising providing a semiconductor donor substrate comprising germanium and / or an A (III) -B (V) semiconductor; Providing at least one first crystal epitaxial layer in the first step (the germanium and / or A (III) -B (V) semiconductor content of the buffer layer of the first layer is In a second step, providing at least one second crystalline epitaxial layer over the first layer (wherein the first layer is the donor substrate and the second layer). Providing at least one insulator layer in the third step (the second layer is provided between the first layer and the insulator layer), In step 4, the structure is And a dividing between the the layer the second layer.

  Due to the reduced content of germanium and / or A (III) -B (V) semiconductor in the buffer layer, at least part of the first layer is provided with very good crystallinity and low defect density As a result, the second crystalline layer provided on the first layer is of high quality. Including germanium and / or A (III) -B (V) semiconductor as a semiconductor donor substrate, the content of germanium and / or A (III) -B (V) semiconductor in the buffer layer is relatively large. It may be reduced to more germanium and / or A (III) -B (V) semiconductors, resulting in greater distortion of the second crystalline layer, such as a silicon layer over the first layer. The method of the present invention has the further advantage that the good electronic properties of the distorted second layer are combined with the advantages of the SOI layer since the second strained layer is provided on top of the insulator layer. The method of the present invention includes a simple series of steps to easily fabricate the semiconductor structure of the present invention.

  In a further embodiment of the invention, the first layer is a single crystal germanium wafer, single crystal A (III) -B (V) semiconductor wafer, epitaxial germanium layer or epitaxial A (III) in the first step. -It is provided on the B (V) semiconductor layer. The substrate supplies a large amount of A (III) -B (V) semiconductor, such as germanium and / or GaAs, and as a result, a high content of germanium and / or A (III) -B (V) semiconductor. One layer grows well on an individual substrate.

  In an advantageous form of the invention, the second layer grows to a thickness of less than 50 nm. At said thickness, the second layer is thermodynamically stable and the second layer can grow with great strain.

  According to another preferred embodiment of the present invention, the germanium and / or A (III) -B (V) semiconductor content of the buffer layer is about 40% to 80% in the first step, Desirably it is reduced to about 50% to 80% or about 60% to 80% germanium. The 40% to 80% percentage of the buffer layer germanium and / or the A (III) -B (V) semiconductor forms a good base for the heavily distorted second layer, whereas the second layer strain A 50% to 80% germanium first layer is more convenient for further enlargement, and a percentage of about 60% to 80% germanium is the most advantageous to produce a very large strain in the second layer. It is a range.

  In yet another advantageous embodiment of the invention, the silicon content of the buffer layer is, in the first step, a ratio of about 20% to 60%, desirably about 20% to 50% or about 20% to 40%. Increased to silicon. A silicon layer with a percentage of about 20% to 60% can grow a heavily strained silicon layer on the first layer, as a result of a large strain on a second layer, such as a silicon layer on the first layer. A percentage of about 20% to 50% silicon is more convenient to achieve, and a percentage of about 20% to 40% silicon is the most effective for producing a very large strain in a second layer such as a silicon layer. It is a convenient range.

  The object is further solved by a semiconductor structure for producing a strained crystal layer on an insulator, the structure comprising a semiconductor donor substrate of a first material comprising germanium and / or an A (III) -B (V) semiconductor; At least one first crystal epitaxial layer, at least one second crystal epitaxial layer, and at least one insulator layer are provided. Here, the first layer is an intermediate layer between the donor substrate and the second layer, the second layer is an intermediate layer between the first layer and the insulator layer, and the first layer Includes a buffer layer having a composition including germanium and / or A (III) -B (V) semiconductor, and the content of germanium and / or A (III) -B (V) semiconductor is from the substrate to the second layer. Has been reduced in direction.

  The structure of the present invention is an intermediate structure for producing a strained crystal layer on an insulator. Reduction of germanium and / or A (III) -B (V) semiconductor content in the buffer layer from the substrate to the second layer results in germanium and / or A (III) -B (V) semiconductor in the buffer layer The content of can be reduced to relatively large amounts of germanium and / or A (III) -B (V) semiconductors, resulting in distortion of the second layer overlying the first layer. Becomes bigger. The proportional decrease in germanium and / or A (III) -B (V) semiconductor further reduces the defect density of at least a portion of the first layer, thereby increasing the quality of the second layer. The structure of the present invention further has the advantage that the SOI structure can be easily formed from the structure of the present invention by placing the second strained layer on the insulator layer.

  In a further preferred embodiment of the invention, the donor substrate is a single crystal germanium wafer, a single crystal A (III) -B (V) semiconductor wafer, an epitaxial germanium layer or an epitaxial A (III) -B (V) semiconductor. Is a layer. The substrate includes a large amount of germanium and / or A (III) -B, which is advantageous for high growth of germanium and / or A (III) -B (V) semiconductor constituting the first layer. (V) Includes semiconductors.

  In another advantageous embodiment of the invention, the content of germanium and / or A (III) -B (V) semiconductor in the first layer is about 40% to 80%, preferably about 50% to Reduced to 80% or about 60% to 80%. A heavily distorted second layer can be grown on top of the first layer by a 40% to 80% germanium and / or A (III) -B (V) semiconductor, A percentage of 50% to 80% is more advantageous to further increase the strain result, and a percentage of about 60% to 80% to achieve a very large strain result on the second layer above the first layer. % Is the most convenient range.

  In another preferred preferred embodiment of the invention, the silicon content of the buffer layer increases in the direction from the substrate to the insulator layer. With this increase in silicon, the lattice of the first layer is adapted to the substrate, so that the defect density of at least some of the first layer is low.

  In a further advantageous embodiment of the invention, the silicon content is increased to a ratio of about 20% to 60%, desirably about 20% to 50% or about 20% to 40% silicon. A large strained second layer, such as a silicon layer, can grow well with a percentage of silicon of about 20% to 60%. In contrast, a percentage of about 20% to 50% of silicon is more advantageous to produce a greater strain result in a second layer such as a silicon layer, and a true strain in the second layer such as a silicon layer. A percentage of about 20% to 40% silicon is the most convenient range to achieve the results.

  In yet another advantageous embodiment of the invention, the first layer and / or the second layer comprises carbon. A low content of carbon, desirably a few percent carbon or even less than 1% carbon, results in highly stable dopants and good property distortions in the first and / or second layers.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 schematically shows a semiconductor substrate 1 used in the first step of the method according to the first embodiment of the invention. The semiconductor substrate 1 is a single crystal germanium wafer, and it is desirable that the wafer has a generally usable size and electronic characteristics. The germanium wafer or donor wafer 1 has a top surface 11 that has been polished and cleaned.

  In another embodiment of the present invention, the semiconductor donor substrate may be an A (III) -B (V) semiconductor wafer such as a GaAs wafer, or an epitaxial Ge layer on top or an epitaxial layer such as a GaAs layer. A substrate provided with an A (III) -B (V) semiconductor layer may be used. For example, the substrate may consist of a GaAs wafer or a GaAs layer covered with a Ge layer.

  FIG. 2 schematically shows the first step of the first embodiment of the present invention. In the first step, a first crystal epitaxial layer 2 is grown on the semiconductor donor substrate 1 shown in FIG. The first crystal epitaxial layer 2 is made of a composition of germanium and silicon forming a GeSi layer. The GeSi layer 2 is placed directly on the upper surface 11 of the germanium wafer 1.

  In yet another embodiment of the present invention, a Ge seed layer may be placed on top surface 11 prior to the growth of GeSi layer 2.

  The GeSi layer 2 consists of two layers, a graded buffer GeSi layer 21 and a relaxed GeSi layer 22. The tilted buffer GeSi layer 21 has a silicon concentration of about 0% in the vicinity of the surface 11 of the germanium wafer 1, but the silicon content of the buffer GeSi layer 21 starts from the surface 11 of the germanium wafer 1 and the silicon content of the GeSi layer in the surface portion 23. The rate gradually increases from about 20% to 60%. Correspondingly, the germanium content of the buffer GeSi layer 21 starts at about 100% at the surface 11 and decreases to about 40% -80% of the germanium percentage at the face portion 23.

  The GeSi layer 2 is doped with less than 1% carbon.

The relaxed GeSi layer is above the surface portion 23 and its silicon to germanium ratio approximately matches the maximum silicon to germanium ratio of the buffer layer 21. In particular, the defect density in the relaxed GeSi layer 22 is very low, about 10 ⁴ cm ⁻² .

  FIG. 3 schematically shows the second step of the first embodiment of the present invention. In the second step, the insulator layer 3 is deposited on the first layer 2, so that the first layer 2 becomes an intermediate layer between the substrate 1 and the insulator layer 3. The insulator layer 3 is made of silicon dioxide and / or silicon nitride. In the illustrated embodiment, the insulator layer 3 is deposited at a temperature below 900 ° C. In another example of the present invention, the insulator layer 3 may be a thermal oxide. The thickness of the insulator layer is matched to the target layer thickness of the SiGe / strained silicon layer that is transferred onto the base wafer. The insulator layer 3 has an upper surface 13.

  The semiconductor structure shown in FIG. 3 is the structure of the invention according to the third embodiment of the present invention, and is an intermediate product for manufacturing a strained crystal layer on an insulator.

FIG. 4 shows the implantation steps applied to the structure shown in FIG. In the implantation step, the structure of FIG. 3 implants hydrogen species 4 with an appropriate energy of less than about 180 keV using an implantation dose greater than 5 × 10 ¹⁶ cm ⁻² . The hydrogen species 4 passes through the upper surface 13, enters the first layer 2 through the insulator layer 3, and proceeds to the surface portion 24 of the first layer 2. Desirably, the surface portion 24 corresponds to the surface portion 23 of the first layer 2 between the buffer GeSi layer 21 and the relaxed GeSi layer 22. By the injection, the surface portion 24 is weakened in advance to form a predetermined divided band.

  In the next step not shown in the figure, the surface 13 of the insulator layer 3 is cleaned with a standard silicon IC and processed after implantation. If necessary, the insulator layer 3 may be removed and a new insulator layer may be deposited.

FIG. 5 shows a bonding step applied to the structure shown in FIG. In the bonding step, the base wafer 6 made of silicon, germanium, A (III) -B (V) semiconductor, quartz, glass or the like is surface-treated, and then the surface-treated insulation having the structure of FIG. It is bonded to the body layer 3. The surface treatment prior to bonding may be performed using chemical mechanical polishing, surface cleaning, oxygen plasma treatment, or other available surface treatment techniques. The base wafer 6 may be bonded directly on the surface 13 of the insulator layer 3. According to another embodiment of the present invention, the base wafer 6 may be provided with a dielectric layer bonded to the surface 13 of the insulator layer 3 on its bonded surface.

  FIG. 6 shows a third step of the method according to the first embodiment of the invention. The third step is a splitting step, in which the structure shown in FIG. 5 is divided into two semiconductor structure portions 31 and 32. Portions 31 and 32 are separated along a predetermined dividing line 24 formed during the implantation step shown in FIG. The resulting portion 31 consists of a base wafer 6 on which the insulator layer 3 is formed, with a portion 7 of the GeSi layer 2 on top of the portion 31. Portion 7 is preferably made of relaxed GeSi material.

  The other part 32 produced by the dividing step consists of the donor germanium wafer 1 on which the remaining part 8 of the GeSi layer 2 is formed. The residual portion 8 is preferably composed of a gradient buffer GeSi layer 21 and a residue of the original relaxed GeSi layer 22.

  In the division processing shown in FIG. 6, parameters generally used in the so-called Smart Cut (trademark) processing described in, for example, WO00 / 24059 incorporated in the present application in a reference format are used. For example, the division may be performed by heat treatment or impact treatment on the structure shown in FIG.

  In a further step not shown, the portion 7 of the GeSi layer 2 is finished by chemical mechanical polishing and optionally by heat treatment.

  FIG. 7 schematically shows a fourth step of the method according to the first embodiment of the invention. In the fourth step, a second crystal epitaxial layer is grown on the surface 17 of the divided portion 31. The second layer 9 is a strained silicon layer having a thickness of less than 50 nanometers and a carbon content of less than 1%. In the strained silicon layer, the strain is very large and the defect density is small.

  The semiconductor structure shown in FIG. 7 is the structure of the invention corresponding to the final product of the method according to the first embodiment of the present invention. The structure comprises a base wafer 6, an insulator layer 3, a portion 7 of the GeSi layer 2, and a second layer 9, where the insulator layer 3 is between the base wafer 6 and the portion 7. It is an intermediate layer, and the portion 7 is an intermediate layer between the insulator layer 3 and the second layer 9. In other embodiments of the present invention, there may be additional layers, such as a seed layer, between each layer of the structure shown in FIG.

  The strain of the silicon layer 9 is strain generated when a crystalline silicon layer having a thickness of less than 50 nm is epitaxially grown on a GeSi layer with a germanium content of about 40 to 80% germanium, and the strain is a germanium content of less than 40%. Greater than the strain of the prior art silicon layer of less than 50 nm thickness grown on the GeSi layer.

  The structure shown in FIG. 7 may be thermally annealed after growth of the strained silicon layer 9.

  8-13 schematically show the steps of the method according to the second embodiment of the invention. 8-15, the same reference numerals that have been used with respect to FIGS. 1-7 are used to indicate the same parts and components of FIGS.

  FIG. 8 schematically shows the semiconductor substrate 1 used in the first step of the second embodiment of the present invention. The semiconductor substrate 1 is a single crystal germanium wafer and has an upper surface 11.

  FIG. 9 shows the first step of the second embodiment of the present invention. In the first step, a fourth crystal epitaxial layer is grown on the upper surface 11 of the germanium wafer 1. As described with reference to FIGS. 1 to 7, in another embodiment, an A (III) -B (V) semiconductor may be used instead of a Ge wafer, or epitaxial Ge or A (III)- A substrate with a B (V) semiconductor layer thereon may be used.

  The first crystal epitaxial layer 2 is a GeSi layer composed of an inclined buffer GeSi layer 21 and a relaxed GeSi 22. The inclined buffer GeSi layer 21 grows on the upper surface 11 of the germanium wafer 1 while gradually increasing the silicon content.

  The silicon content starts at a percentage of about 0% at the surface 11 and increases to a percentage of about 20% to 60% of silicon at the face portion 23 of the first layer 2. Above the surface portion 23, the relaxed GeSi 22 grows with an almost constant silicon to germanium ratio, which roughly matches the maximum silicon to germanium ratio of the graded buffer GeSi layer 21. Correspondingly, the germanium content of the graded buffer layer 21 decreases from a germanium content of about 100% at the surface 11 to a germanium content of about 40% to 80% at the face portion 23. The GeSi layer 2 is doped with less than 1% carbon. The first layer 2 has a top surface 12.

  FIG. 10 schematically shows a second step of the method according to the second embodiment of the invention. In the second step, a second crystal epitaxial layer 9 having a carbon content of less than 1% is grown on the first layer 2. The second crystal epitaxial layer 9 is a strained silicon layer having a thickness of less than 50 nm. In the strained silicon layer 9, the crystal defect density is very small and the strain is large. The second layer has a top surface 19.

  FIG. 11 schematically shows a third step of the method according to the second embodiment of the invention. In the third step, the insulator layer 3 is deposited on the surface 19 of the strained silicon layer 9. The insulator layer 3 is made of silicon dioxide and / or silicon nitride. The thickness of the insulator layer 3 depends on the target layer signal of the SiGe / strained silicon layer transferred onto the base wafer. The insulator layer 3 has an upper surface 13.

  FIG. 12 shows the implantation steps applied to the structure 40 shown in FIG. In the implantation step, hydrogen species 4 is implanted through the upper surface 13 and the insulator layer 3 to near the surface portion of the original surface 12 that forms the interface between the GeSi layer 2 and the strained silicon layer 9. By the injection, the interface 12 is weakened in advance, and as a result, a predetermined dividing band is provided in the interface 12.

The implantation is done with a suitable energy of less than about 180 keV with a hydrogen dose greater than 5 × 10 ¹⁴ cm ⁻² .

  After the implantation, the surface 13 is cleaned with a standard silicon IC and processed after the implantation. If necessary, the insulator layer 3 may be removed and a new insulator layer may be deposited. This step is not shown.

  Then, the surface treatment to the structure shown in FIG. 12 and the surface treatment to the base wafer are continued, and the base wafer is made of silicon, germanium, A (III) -B (V) semiconductor, quartz And glass. The surface treatment may be performed using chemical mechanical polishing, surface cleaning, oxygen plasma treatment, or similar treatment.

  FIG. 13 shows a bonding step in which the structure shown in FIG. 12 is bonded to the base wafer 6. The base wafer 6 is bonded on the surface 13 of the insulator layer 3. According to another embodiment of the present invention, the base wafer 6 may be provided with an insulator layer bonded to the surface 13 of the insulator layer 3 on the bonded surface.

  FIG. 14 shows a fourth step in the method according to the second embodiment of the present invention. In the fourth step, the structure shown in FIG. 13 is divided into two parts 41 and 42. The division step is performed in the same manner as the division step of the Smart Cut (trademark) process in which the structure is separated into two parts along a predetermined division line, and is performed by, for example, heat treatment or impact treatment.

  In FIG. 14, the dividing line between the portions 41 and 42 coincides with a predetermined dividing band of the interface 12 between the first layer 2 and the second strained silicon layer 9. The first divided portion 41 is composed of a base wafer 6 on which the insulator layer 3 is formed, and is provided with a strained silicon layer 9 on the top, so that the insulator layer 3 is composed of the base wafer 6 and the strained layer 9. Become the middle layer between. In other embodiments of the present invention, additional layers may be disposed between the base wafer 6 and the insulator layer 3 and / or between the insulator layer 3 and the strained layer 9. The divided part 42 consists of a donor germanium wafer 1 on which the GeSi layer 2 is formed.

  FIG. 15 schematically shows the final product of the method according to the second embodiment of the present invention, which corresponds to the segment 41 shown in FIG. The structure 41 may be thermally annealed and the GeSi residue on the strained silicon layer 9 may be removed.

Distortion in the strained silicon layer 9 of the structure 41 shown in FIG. 15 is very large defect density is very low and less than ¹⁰ 4 ^{cm -2.} The strain of the silicon layer 9 is strain generated when a crystalline silicon layer having a thickness of less than 50 nm is epitaxially grown on a GeSi layer with a germanium content of about 40 to 70% germanium, and the strain is a germanium content of less than 40%. Greater than the strain of the prior art silicon layer of less than 50 nm thickness grown on the GeSi layer.

  FIG. 16 schematically shows the concentration distribution versus thickness of the semiconductor structure shown in FIGS. The same reference numerals in FIG. 16 as those used in FIGS. 2 to 9 indicate the same components in FIGS.

  In FIG. 16, the solid line 51 indicates the germanium content of the semiconductor structure shown in FIGS. 2 to 9, and the germanium content is about 100% in the germanium substrate 1. A broken line 52 indicates the silicon content of the semiconductor structure shown in FIGS. 2 to 9, and the silicon content is about 0% in the germanium substrate 1. The silicon content 52 is increased from 0% to about 30% in the graded buffer GeSi layer 21, while the germanium content 51 is decreased to a value of about 70% in the buffer layer 21. In FIG. 16, the increase in silicon 52 and the decrease in germanium 51 are shown to be continuous. Instead of a continuous change, a gradual or gradual change in the silicon and / or germanium content may work in the buffer layer 21. Furthermore, the buffer layer 21 may have one or more regions where the germanium and / or silicon content does not change.

In the relaxed GeSi layer 22 above the buffer layer 21, the germanium to silicon ratio is approximately constant, about 30-60% silicon to about 40-70% germanium. The relaxed GeSi layer 22 has almost no dislocations. The crystal defect density of the relaxed GeSi layer 22 is less than 10 ⁴ cm ⁻² .

  The preferred embodiment described above used the Smart Cut ™ technology for layer transfer, but any other layer transfer technology such as Bond-and-Etchback technology or other weakening technology using porous layer formation. May be applied.

1 schematically shows a semiconductor substrate used in a first step of a method according to a first embodiment of the invention. 1 schematically shows a first step of a first embodiment of the present invention. Fig. 4 schematically shows a second step of the first embodiment of the invention resulting in a semiconductor structure according to the third embodiment of the invention. Fig. 4 schematically shows an implantation step applied to the structure shown in Fig. 3; 5 schematically shows a step of bonding to the structure shown in FIG. Fig. 6 schematically shows a division step for the structure shown in Fig. 5 according to a third step of the first embodiment of the invention. 1 schematically shows an inventive semiconductor structure manufactured by the method according to the first embodiment of the invention shown in FIGS. The semiconductor substrate used at the 1st step of the 2nd Embodiment of this invention is shown roughly. 1 schematically shows a first step of a second embodiment of the present invention. Fig. 3 schematically shows a second step according to a second embodiment of the invention. Fig. 6 schematically shows a third step of the second embodiment of the invention resulting in a semiconductor structure according to the fourth embodiment of the invention. 12 illustrates an implantation step applied to the structure shown in FIG. FIG. 13 shows a bonding step applied to the structure shown in FIG. FIG. 14 shows a fourth step of the method according to the second embodiment of the present invention to which the structure shown in FIG. 13 is applied. Fig. 15 schematically shows an inventive structure manufactured by a method according to a second embodiment of the invention schematically shown in Figs. 10 schematically shows the concentration distribution versus thickness of the semiconductor structure shown in FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor donor substrate 2 ... 1st crystal epitaxial layer 3 ... Insulator layer 6 ... Semiconductor base substrate 7 ... Part of GeSi layer 2 (1st layer of division | segmentation)
9 ... Second crystal epitaxial layer 21 ... Buffer layer

Claims (25)

A method for producing a strained silicon layer on an insulator layer (3) , comprising:
Providing a semiconductor donor substrate (1) comprising germanium and / or GaAs ;
In the first step, a first crystal epitaxial layer (2) having a composition of at least one germanium and silicon is provided, and the buffer layer (21) of the first layer (2) is provided during the first step. Reducing the germanium content ,
In a second step, at least one insulator layer (3) is provided, wherein the first layer (2) is provided between the substrate (1) and the insulator layer (3). Being a thing,
Dividing the first layer (2) in a third step;
Providing a second crystal epitaxial layer (9), which is at least one strained silicon layer, on the divided first layer (7) in a fourth step. The first layer (2) is provided in the first step on a single crystal germanium wafer (1), a GaAs wafer, and a semiconductor donor substrate provided with an epitaxial germanium layer or an epitaxial GaAs layer on top. The method according to claim 1. The content of germanium in the buffer layer (21) is reduced in the first step to a ratio of about 40-80%, preferably about 50-80% or about 60-80%. Item 3. The method according to Item 1 or 2.   The silicon content of the buffer layer (2) is increased in the first step to a ratio of about 20-60%, preferably about 20-50% or about 20-40% silicon. The method according to claim 1.   The method according to claim 1, wherein the second layer is grown to a thickness of less than 50 nm. To manufacture a semiconductor structure having a semiconductor base substrate (6), at least one insulator layer (3), a divided first layer (7), and a second crystalline epitaxial layer (9),
Prior to the third step, the semiconductor donor substrate (1) having the first layer (2) and the insulator layer (3) is further bonded to a semiconductor base substrate (6). The method according to any one of claims 1 to 5.   In the fourth step, by providing the second crystal epitaxial layer (9) on the divided first layer (7), the semiconductor base substrate (6), the insulator layer (3) Method according to claim 6, characterized in that a semiconductor structure is obtained in which the divided first layer (7) and the second crystal epitaxial layer (9) are stacked in this order.   The method according to claim 6 or 7, characterized in that the first layer (2) and / or the second layer (9) comprises carbon. A semiconductor structure for producing a strained silicon layer on an insulator layer (3) ,
A semiconductor donor substrate (1) of a first material comprising germanium and / or GaAs ;
A crystal epitaxial layer (2) comprising a composition of at least one germanium and silicon ;
At least one insulator layer (3),
The at least one crystal epitaxial layer (2) is an intermediate layer between the donor substrate (1) and the insulator layer (3), and the at least one crystal epitaxial layer (2) is composed of germanium and silicon. A structure comprising a buffer layer (21) of composition , wherein the germanium content is reduced in the direction from the substrate (1) to the insulator layer (3). 10. Structure according to claim 9, characterized in that the donor substrate is a single crystal germanium wafer (1), a GaAs wafer, a substrate comprising an epitaxial germanium layer or an epitaxial GaAs layer on the top surface . 11. The content of germanium in the buffer layer (21) is reduced to a ratio of about 40-80%, desirably about 50-80% or about 60-80%. Description structure.   The silicon content of the first layer (2) is increased in the direction from the substrate (1) to the insulator layer (3). Description structure.   13. The structure of claim 12, wherein the silicon content is increased to about 20-60% silicon, desirably about 20-50% or about 20-40% silicon. 14. A structure according to any one of claims 9 to 13, characterized in that the first layer (2) contains carbon . A method for producing a strained silicon layer on an insulator layer (3) , comprising:
Providing a semiconductor donor substrate (1) comprising germanium and / or GaAs ;
In the first step, a first crystal epitaxial layer (2) having a composition of at least one germanium and silicon is provided, and the germanium content in the buffer layer (21) of the first layer (2) is set. Reducing during the first step,
In the second step, a second crystal epitaxial layer (9), which is at least one strained silicon layer, is provided, the first layer (2) being the donor substrate (1) and the second layer. (9) that it is provided between,
In the third step, at least one insulator layer (3) is provided, and the second layer (9) is interposed between the first layer (2) and the insulator layer (3). Be provided,
Dividing the structure between the first layer (2) and the second layer (9) in a fourth step. The first layer (2) is provided in the first step on a single crystal germanium wafer (1), a GaAs wafer, and a semiconductor donor substrate provided with an epitaxial germanium layer or an epitaxial GaAs layer on top. The method according to claim 15. 17. Method according to claim 15 or 16, characterized in that the second layer (9) is grown to a thickness of less than 50 nm. The content of germanium in the buffer layer (21) is reduced in the first step to a ratio of about 40-80%, desirably about 50-80% or about 60-80%. Item 18. The method according to any one of Items 15 to 17.   The silicon content of the buffer layer (21) is increased in the first step to a ratio of about 20-60%, preferably about 20-50% or about 20-40% silicon. The method according to any one of claims 15 to 18. A semiconductor structure for producing a strained silicon layer on an insulator layer (3) , comprising:
A semiconductor donor substrate (1) of a first material comprising germanium and / or GaAs ;
A first crystalline epitaxial layer (2) comprising a composition of at least one germanium and silicon ;
A second crystalline epitaxial layer (9) which is at least one strained silicon layer ;
At least one insulator layer (3),
The first layer (2) is an intermediate layer between the donor substrate (1) and the second layer (9), and the second layer (9) is the first layer (2). And the insulator layer (3), the first layer (2) includes a buffer layer (21) composed of germanium and silicon, and the germanium content is the substrate. Structure reduced in the direction from (1) to the second layer (9). 21. Structure according to claim 20, characterized in that the donor substrate is a single crystal germanium wafer (1), a GaAs wafer, a substrate comprising an epitaxial germanium layer or an epitaxial GaAs layer on the top surface . 22. The content of germanium in the buffer layer (21) is reduced to a ratio of about 40-80%, desirably about 50-80% or about 60-80%. Construction.   The silicon content of the buffer layer (21) is increased in the direction from the substrate (1) to the insulator layer (3). Construction.   24. The structure of claim 23, wherein the silicon content is increased to about 20-60% silicon, desirably about 20-50% or about 20-40% silicon. 25. A structure according to any one of claims 20 to 24, characterized in that the first layer (2) and / or the second layer (9) comprises carbon.

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