Recrystallization method applied to inert gas injection damaged crystal materials

Abstract

The application provides a recrystallization method of a crystal material, comprising the following steps: depositing a covering layer on the surface of the crystal material; irradiating one side of the crystal material with the covering layer deposited thereon by using a pulse laser, so that the crystal material is heated and cooled to crystallize, and a recrystallization layer is formed on the side of the crystal material close to the covering layer; and etching the covering layer on the surface of the crystal material to expose the recrystallization layer. By pre-depositing the covering layer on the surface of the crystal material and annealing the crystal material by using the pulse laser, the high-quality regeneration of the crystal material is realized, and the problem of loss of doped atoms is effectively inhibited.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor technology, and in particular, to a recrystallization method of a crystal material. BACKGROUND

[0002] At present, in the field of semiconductors, supersaturated doped crystal materials and crystal materials containing inert gas atoms are widely used. Supersaturated doped crystal materials have great potential in the fields of new generation visible-infrared integrated detectors, broad spectrum absorption solar cells, etc. due to their novel characteristics such as deep level metal insulator phase transition and extended sub-bandgap absorption. The bubbles formed by inert gas atoms (such as helium atoms and neon atoms) have been proven to be applicable in many fields such as adsorption of metal impurities in matrix materials or strain relaxation of silicon heterojunctions, preparation of silicon / germanium on insulator (intelligent cutting), etc.

[0003] In order to achieve supersaturation doping and break through the limitation of material solid solubility, technicians in the field often use ion implantation, a non-equilibrium doping technology, to dope impurity atoms far exceeding the solid solubility into the matrix material. In this process, due to the collision of impurity ions, the lattice structure of the matrix material within a certain depth of the surface will be damaged, and even an amorphous structure without order will be formed. On the other hand, inert gas atoms have a full-shell electron structure and mainly interact with the matrix through physical action. After being implanted into the matrix by ion implantation, they are difficult to form bonds with the matrix atoms directly except for inducing defects, and will only be captured by existing defects such as vacancies or cavities to form nano-bubble structures.

[0004] Whether it is to repair the damaged lattice structure of the surface of the supersaturated doped crystal material and activate the doped atoms, or to induce the regrowth of inert atom bubbles and eliminate the residual crystal defects between the bubbles, in order to meet the special application of supersaturated doped crystal materials and inert atom bubble crystal materials in electrical and optical aspects, the above-mentioned crystal materials need to be subjected to certain heat treatment.

[0005] The prior art usually adopts two traditional heat treatment methods of high-temperature furnace annealing and rapid thermal annealing, but the actual effect is not ideal. For supersaturated doped crystal materials, since the solid solubility of n-type or p-type impurities in semiconductor materials is relatively low, generally not more than 10 16 / cm 3The solid solubility of deep level impurities such as chalcogen elements (sulfur, selenium, tellurium) and transition metal elements is lower, which leads to a large amount of diffusion and loss of doping atoms during the annealing and cooling crystallization stage of the substrate, so it is very difficult to achieve high-quality crystallization and supersaturation doping by using conventional thermal annealing. For the crystal material containing inert atom bubbles, under the action of traditional long-time thermal annealing, the bubbles will escape from the substrate in large quantities (leaving holes), and the inert atoms in the bubbles and interstitial sites will interfere with the crystallization process, resulting in that the residual defects outside the crystal cannot be completely eliminated, and the quality of the crystal cannot be fundamentally improved. For the above reasons, high-quality supersaturation doped crystal materials and crystal materials containing inert gas atoms cannot be obtained so far, which has been greatly limited in the application of semiconductor devices. SUMMARY

[0006] (I) Technical problems to be solved

[0007] The present application provides a recrystallization method of a crystal material, which is used to at least partially solve one of the above technical problems.

[0008] (II) Technical solutions

[0009] In one aspect, the present application provides a recrystallization method of a crystal material, comprising: depositing a covering layer on the surface of the crystal material; irradiating the side of the crystal material with the covering layer by using a pulsed laser to heat and cool the crystal material to crystallize, and form a recrystallization layer on the side of the crystal material close to the covering layer; and etching the covering layer on the surface of the crystal material to expose the recrystallization layer.

[0010] Optionally, the covering layer is formed by depositing silicon dioxide, silicon nitride or aluminum oxide on the surface of the crystal material.

[0011] Optionally, the thickness of the covering layer is 10 nm-50 nm.

[0012] Optionally, the covering layer is deposited by chemical vapor deposition, reactive magnetron sputtering or atomic layer deposition.

[0013] Optionally, the chemical vapor deposition comprises plasma-enhanced chemical vapor deposition or low-pressure chemical vapor deposition.

[0014] Optionally, when the side of the crystal material with the covering layer is irradiated by using a pulsed laser, the period of the pulsed laser can be set to nanoseconds, picoseconds or femtoseconds.

[0015] Optionally, the crystal material is a crystal material containing an inert atom bubble layer or a crystal material containing a crystal lattice damage layer.

[0016] Optionally, when the one side of the crystal material deposited with the covering layer is irradiated by the pulsed laser, the melting depth of the crystal material is greater than the depth of the bubble layer or the lattice damage layer by adjusting the parameters of the pulsed laser.

[0017] Optionally, the covering layer is etched by a plasma etching method or a chemical wet etching method.

[0018] Optionally, the lattice damage layer of the crystal material contains impurity atoms.

[0019] (Three) beneficial effects

[0020] The recrystallization method of the crystal material provided by the application at least has the following beneficial effects:

[0021] 1. The crystal material in the application has a covering layer deposited on the surface, and the covering layer has a physical blocking effect, which can effectively reduce the diffusion and escape phenomenon of supersaturated doping atoms and inert atom bubbles, and can avoid the surface ablation effect caused by the pulsed laser annealing process and the impurity loss and bubble loss phenomenon caused by the evaporation of the molten liquid phase layer due to high temperature.

[0022] 2. The one side of the crystal material deposited with the covering layer is irradiated by the pulsed laser. The pulsed laser annealing causes the liquid phase epitaxial crystallization mechanism, which has the characteristics of high crystallization rate and short annealing period, and can completely eliminate the defects between the bubbles. In addition, the pulsed laser technology has the advantage of accurate positioning during irradiation, and will not affect the structure and function of the surrounding and lower structure during irradiation of the area to be processed, so the technical scheme of the application can be applied to three-dimensional complex structure crystallization to realize spatial three-dimensional localized annealing.

[0023] 3. The covering layer technology and the pulsed laser annealing technology involved in the application are compatible with the existing silicon CMOS process, are not affected by the size of the substrate, can be batch processed, and are efficient and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flowchart of the recrystallization method of the crystal material containing inert atom bubbles in an embodiment of the application is schematically shown;

[0025] Figures 2A-2D The structure diagram corresponding to each operation of the recrystallization method of the crystal material containing inert atom bubbles in the embodiment of the application is schematically shown;

[0026] Figure 3A The cross-sectional transmission electron microscope characterization result of the crystal germanium material containing Ar atom bubbles in the embodiment of the application is schematically shown;

[0027] Figure 3BSchematic representation of the cross-section TEM characterization of the surface region of the germanium substrate after pulsed laser annealing of the crystal material containing inert atom bubbles in the embodiment of the present application;

[0028] Figure 3C Schematic representation of the high-resolution TEM characterization of the bubble layer of the germanium substrate after pulsed laser annealing of the crystal material containing inert atom bubbles in the embodiment of the present application;

[0029] Figures 4A-4D Schematic representation of the structure corresponding to each operation of the recrystallization method of the crystal material containing Ar ion implantation damage in the embodiment of the present application;

[0030] Figure 5A Schematic representation of the TEM characterization of the surface lattice damage layer caused by Ar ion implantation of the substrate germanium material in the embodiment of the present application;

[0031] Figure 5B Schematic representation of the high-resolution TEM characterization of the lattice damage layer after pulsed laser irradiation in the embodiment of the present application;

[0032] Figure 5C Schematic representation of the secondary ion mass spectrometry test results of the Ar atom distribution of the surface damage layer of the crystal germanium material before and after pulsed laser annealing in the embodiment of the present application.

[0033] Legend of reference signs:

[0034] 200 - crystal material; 201 - bubble layer; 202 - cover layer; 203 - pulsed laser; 204 - recrystallization layer; 401 - lattice damage layer DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the embodiments and the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0036] The terms used herein are only used to describe specific embodiments, and are not intended to limit the present application. The terms "include", "contain" and the like used herein indicate the existence of the described features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0037] In the present application, unless specifically defined otherwise and limited in the specification, the terms "mount", "connect", "connection", "fixed", and the like, should be construed broadly and do not necessarily require a direct mechanical connection, but can also include an indirect connection through an intermediate medium, and can be a mechanical connection, an electrical connection or can be in communication with each other, and can be a direct connection or an indirect connection through an intermediate medium, or an internal communication of two elements or an interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "length", "circumferential", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and does not indicate or imply that the subsystems or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0039] Throughout the drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in understanding the present application, conventional structures or configurations will be omitted. Also, the shape, size, positional relationship of the components in the drawings do not reflect the true size, scale and actual positional relationship. In addition, in the claims, any reference symbol located between parentheses should not be construed as a limitation on the claims.

[0040] Similarly, in order to simplify the present application and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present application, various features of the present application are sometimes grouped together in a single embodiment, figure or description thereof. The description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0041] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0042] The present application aims to provide a recrystallization method of a crystal material, which can regenerate a crystal material containing inert atom bubbles or a crystal lattice damage layer with high quality.

[0043] A conventional thermal annealing method is to place the whole sample in a vacuum furnace at a certain temperature, and then take it out after several seconds to several minutes to adjust the internal microstructure of the substrate and eliminate internal defects of the substrate. The method belongs to a solid phase epitaxial crystallization mechanism. It is proved that the solid phase epitaxial crystallization mechanism cannot completely eliminate the defect structure of the sample, and has many disadvantages such as decomposition of the substrate material, precipitation of the dopant, and surface pollution.

[0044] The liquid phase epitaxial crystallization mechanism based on pulsed laser annealing adopted by the present application is a non-equilibrium doping crystallization mechanism. When the pulsed laser irradiates the surface of the substrate material at an energy density higher than the melting threshold of the substrate material, melting occurs. The melting front penetrates into the substrate material from top to bottom at a high speed (~ 10 m / s) until the irradiation ends. At this time, the surface liquid layer cools and solidifies by releasing heat through the un-melted substrate matrix area at the bottom, and the melting front returns to the surface from bottom to top at a high speed (~ 3 m / s). The whole process is called non-equilibrium liquid phase epitaxial regeneration.

[0045] The present application aims to provide a recrystallization method of a crystal material, which can regenerate a crystal material containing inert atom bubbles or a crystal lattice damage layer with high quality.

[0046] The present application will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0047] An embodiment of the present application provides a recrystallization method of a crystal material containing inert atom bubbles.

[0048] Figure 1 A flowchart of the recrystallization method of the crystal material 200 containing inert atom bubbles in an embodiment of the present application is schematically shown. Figures 2A-2D Structural diagrams corresponding to each operation of the recrystallization method of the crystal material 200 containing inert atom bubbles in an embodiment of the present application are schematically shown.

[0049] As Figure 1 As shown in FIG. 1 and FIG. 2, the recrystallization method may, for example, include operation S110 to operation S130.

[0050] In operation S110, a layer of covering layer 202 is deposited on the surface of the crystal material 200 containing the bubble layer 201.

[0051] In the embodiment, the bubble layer 201 on the surface of the crystal material 200 is formed by injecting inert gas into the crystal material 200, as shown in FIG. 1. Figure 2A ​

[0052] Beam Ion Implantation (BII) or Plasma Immersion Ion Implantation (PIII) can be used to implant inert gas into the crystal material.

[0053] It should be noted that, no matter which ion implantation technology is selected, the inert atom implantation dose is generally greater than 1×10 16 / cm 2 , and the implantation energy is greater than 10 kV, so as to form a bubble layer on the surface of the crystal material 200.

[0054] The crystal material 200 can be an elemental semiconductor material or a compound semiconductor material. The structure of the crystal material 200 is a bulk structure or a thin film structure.

[0055] In the embodiment of the present application, a germanium substrate with a bulk structure and inert atom argon (Ar) are taken as an example, wherein the size of the germanium substrate is 2 inches, the resistance is 0.01-0.1 Ω·cm, and the crystal phase is <110>.

[0056] In the embodiment of the present application, BII is selected to implant inert gas Ar into the germanium substrate, the implantation energy is 30 kV, and the implantation dose is 1×10 17 / cm 2 .

[0057] The material of the cover layer 202 deposited on the surface of the crystal material 200 includes but is not limited to SiO2, and can also be Si3N4 or Al2O3, for example. The thickness of the cover layer 202 is 10 nm-50 nm, and preferably 20 nm.

[0058] The cover layer 202 has the characteristics of uniformity, compactness and continuity, which not only can inhibit the diffusion and escape phenomenon of the bubbles, but also can alleviate the surface evaporation effect of the high-temperature molten layer, and effectively reduce the loss of the bubbles.

[0059] It should be noted that, no matter which type and thickness of the cover layer 202 is selected, the cover layer 202 should completely cover the surface of the crystal material 200.

[0060] The preparation method of the covering layer can be chemical vapor deposition (CVD), reactive magnetron sputtering (MS) or atomic layer deposition (ALD), wherein the chemical vapor deposition method can include plasma enhanced chemical vapor deposition (PECVD) or low-pressure chemical vapor deposition (LPCVD).

[0061] The embodiment of the present invention adopts PECVD to prepare the cover layer 202. The specific process parameters include: power of 60 W, working pressure of 600 mTor, deposition time of 4 min, deposition temperature of 500°C, and flow rates of working gases SiH4, H2 and O2 of 125 sccm, 225 sccm and 450 sccm respectively.

[0062] The prepared covering layer 202 should be deposited on the surface of the bubble layer 201 of the crystal material 200, such as Figure 2B shown.

[0063] In operation S120 , a pulsed laser 203 is used to irradiate the side of the crystal material 200 where the cover layer 202 is deposited, so that the crystal material 200 is heated, cooled, and recrystallized, forming a recrystallized layer 204 on the side of the crystal material 200 close to the cover layer 202 .

[0064] The pulse laser includes but is not limited to nanosecond pulse laser, and may also be picosecond pulse laser or femtosecond pulse laser.

[0065] The present invention is implemented as follows Figure 2C As shown, when the pulse laser 203 is irradiated on one side of the crystal material 200 deposited with the covering layer 202, the pulse laser 203 used is a XeCl excimer pulse laser, but this does not mean that only this pulse laser can be used. The use of other types of pulse laser technology should also be included in the scope of protection of the present invention.

[0066] The parameters of the XeCl excimer pulse laser in the embodiment of the present invention include: laser wavelength of 308 nm, pulse period of 28 ns, pulse laser energy density of 800 mJ / cm 2 , the number of pulses is 1.

[0067] It should be noted that, no matter what pulse laser annealing parameters are adopted, the melting depth of the crystal material 200 should be greater than the depth of the bubble layer 201 to enter the substrate region, so as to provide high-quality seeds for liquid phase epitaxial regrowth of the substrate region. In addition, since the effective penetration depth of the pulse laser is limited, the depth of the bubble layer 201 on the surface of the crystal material 200 should generally not exceed 300 nm.

[0068] In operation S130, the capping layer 202 on the surface of the crystal material 200 is etched to expose the recrystallized layer 204.

[0069] The capping layer 202 can be etched by using a plasma etching method or a chemical wet etching method.

[0070] In the embodiment of the present application, the chemical wet etching method is used to etch the capping layer 202, and the chemical reagent used is hydrofluoric acid (HF), and the etching time is 30 s, wherein the concentration of HF is 1% to 5%, and preferably 3%. After the etching is completed, the crystal material 200 can be ultrasonically cleaned with alcohol and deionized water for 3 minutes, respectively, in sequence, to remove the residual HF solution, and the crystal material 200 is blown dry by a nitrogen gun after cleaning, to obtain the crystal material 200 containing the recrystallized layer 204, as shown in Figure 2D .

[0071] In order to more comprehensively prove that the technical scheme of the present application can effectively obtain a high-quality recrystallized layer, the crystal structure before and after pulse annealing in the embodiment of the present application is observed, for example, the cross-sectional structure of the crystal material can be characterized by using a transmission electron microscope, and the structure is as shown in Figures 3A-3C .

[0072] Figure 3A The cross-sectional transmission electron microscope characterization result of the crystal germanium material containing Ar atom bubbles in the embodiment of the present application is schematically shown.

[0073] According to the embodiment of the present application, under the adopted beam current type ion implantation conditions, a large number of bubble structures are generated on the surface of the crystal germanium, the bubble size gradually decreases from the surface to the inside, and the density gradually increases. The depth of the bubble layer is about 70 nm, and the ring pattern result of selected area diffraction confirms that the bubble layer has been completely amorphized. The lattice arrangement of the single crystal substrate region below the surface amorphous layer is good, according to the liquid phase epitaxial crystallization theory, when the surface melting layer depth reaches below the amorphous / single crystal interface, the surface bubble layer will obtain high-quality regrowth after cooling.

[0074] Figure 3B The cross-sectional transmission electron microscope characterization result of the surface region of the germanium substrate after pulse laser annealing in the embodiment of the present application is schematically shown.

[0075] According to the embodiment of the present application, after the treatment of the pulsed laser irradiation, the bubble density is reduced and the size is increased, which indicates that the bubble fusion phenomenon occurs in the rapid liquid phase epitaxial crystallization process, and the selected area diffraction pattern shows that the crystal quality of the bubble layer is significantly improved.

[0076] Figure 3C The high-resolution transmission electron microscopy characterization results of the germanium substrate bubble layer after the pulsed laser annealing in the embodiment of the present application are schematically shown.

[0077] The high-resolution characterization results prove that the germanium crystal lattice between the bubbles is well arranged without visible defects, which indicates that the damaged bubble layer is regenerated with high quality.

[0078] In the traditional thermal annealing process, the bubble layer on the surface of the substrate and the matrix region at the bottom are heated synchronously, the temperature gradient of the crystallization interface is very small, thereby resulting in a low crystallization rate (~10 -10 m / s), and the matrix atoms can only rearrange at the solid phase crystallization interface through a limited distance (about several atomic spacings). If the crystallization interface encounters the bubble structure in the process of slow movement, the lattice rearrangement is likely to be disturbed, causing bonding errors. These bonding errors caused by the bubble interference will continuously accumulate with the movement of the crystallization interface, and finally form larger micro-twin and dislocation defects, resulting in poor quality of the recrystallized layer. Therefore, the traditional thermal annealing method cannot achieve the ideal effect for treating the crystal material containing inert atom bubble structure.

[0079] The recrystallization method provided by the present application adopts the pulsed laser annealing method. The irradiation of high-energy pulsed laser can cause the phase transition of the surface bubble layer of the crystal material. In the subsequent cooling and crystallization process, the matrix atoms can migrate in a large range in the high-temperature liquid phase layer, so as to find the low-energy bonding site at the crystallization interface. The pulse width of the pulsed laser makes the solid-liquid crystallization interface have a very high temperature gradient, thereby obtaining a high crystallization rate (~3 m / s). The ultra-high crystallization rate can keep the bubbles in a highly dynamic process before being captured by the solidification interface, so as to avoid the defect accumulation caused by the interference of the crystallization interface, thereby obtaining a high-quality recrystallized layer. In addition, the present application deposits a covering layer with a proper thickness on the surface of the crystal material before the pulsed laser annealing. The covering layer can effectively suppress the bubble diffusion and escape phenomenon, and can also alleviate the surface evaporation of the high-temperature molten layer, thereby effectively reducing the bubble loss phenomenon in the pulsed laser annealing process.

[0080] In the present application, the pulsed laser technology can be accurately positioned when irradiating the region to be treated, and will not affect the structure and function of the surrounding and lower structure of the irradiation region, and therefore can be applied to the crystallization of three-dimensional complex structures. The surface covering layer technology and the pulsed laser annealing technology in the present application are both compatible with the CMOS process, and therefore can be used on a large scale in the existing semiconductor technology industry.

[0081] Another embodiment of the present application provides a recrystallization method of a crystal material containing an Ar atom lattice damage layer (without bubbles).

[0082] Figure 1 A flow chart of a recrystallization method of a crystal material 200 with a surface lattice damage layer in another embodiment of the present application is schematically shown. Figures 4A-4D A structure diagram corresponding to each operation of a recrystallization method of a crystal material 200 with a surface lattice damage layer in an embodiment of the present application is schematically shown.

[0083] As Figure 1 As shown in FIG. 4, the recrystallization method may, for example, include operations S110-S130.

[0084] In operation S110, a covering layer 202 is deposited on the crystal material 200 with a surface lattice damage layer 401 containing impurity atoms.

[0085] In the embodiment, the lattice damage layer 401 on the surface of the crystal material 200 is formed by injecting doping atoms into the crystal material 200, as shown in FIG. 2. Figure 4A

[0086] The crystal material 200 may be an elemental semiconductor material or a compound semiconductor material. The structure of the crystal material 200 includes but is not limited to a bulk structure or a thin film structure.

[0087] In the embodiment, a germanium substrate with a bulk structure is taken as an example, wherein the size of the germanium substrate is 2 inches, the resistance is 0.01-0.1 Ω·cm, and the crystal phase is <110>.

[0088] In the embodiment, the ion implantation technology includes but is not limited to a beam ion implantation technology (BII) and a plasma immersion ion implantation technology (PIII). In the embodiment, the PIII is adopted, and the process parameters include: a discharge power of 500 W, an argon pressure in a working chamber of 10 Pa, a pulse negative high voltage of 6 kV, a pulse width of 10 μs, and a frequency of 1 kHz. -3

[0089] In the embodiment, the surface of the crystal material 200 is cleaned by an ultrasonic process before the covering layer 202 is deposited. The cleaning sequence and time may be acetone for 5 min, ethanol for 5 min, and deionized water for 5 min in sequence. After the ultrasonic cleaning, the crystal material 200 is dried by a nitrogen gun. The ultrasonic process cleaning can effectively remove the impurities and natural oxides on the surface of the crystal material 200.​​

[0090] The material of the cover layer 202 deposited on the surface of the crystal material 200 includes but is not limited to SiO2, and can also be Si3N4 or Al2O3. The thickness of the cover layer 202 is 10 nm-50 nm, and preferably 20 nm.

[0091] It should be noted that no matter what type and thickness of the cover layer 202 is selected, the cover layer 202 should completely cover the surface of the crystal material 200, and the cover layer 202 has the characteristics of uniformity, density and continuity.

[0092] The preparation method of the cover layer can be chemical vapor deposition (CVD), reactive magnetron sputtering (MS) or atomic layer deposition (ALD), wherein the chemical vapor deposition includes but is not limited to plasma enhanced chemical vapor deposition (PECVD) or low-pressure chemical vapor deposition (LPCVD).

[0093] The embodiment of the present application adopts PECVD to prepare the cover layer 202, and the specific process parameters include: power 60 W, working pressure 600 mTor, deposition time 4 min, deposition temperature 500℃, and the flow rates of working gases SiH4, H2 and O2 are 125 sccm, 225 sccm and 450 sccm respectively. The prepared cover layer 202 should be deposited on the surface of the crystal material 200 containing the lattice damage layer 401, as shown in Figure 2B .

[0094] In operation S420, the one side of the crystal material 200 deposited with the cover layer 202 is irradiated by the pulsed laser 203, so that the crystal material 200 is heated and cooled to recrystallize, and the recrystallization layer 204 is formed on the side of the crystal material close to the cover layer 202.

[0095] The pulsed laser 203 includes but is not limited to nanosecond pulsed laser, and can also be picosecond pulsed laser or femtosecond pulsed laser.

[0096] The embodiment of the present application can be used for Figure 4CThe pulse laser 203 used for irradiating the side of the crystal material 200 deposited with the cover layer 202 is XeCl excimer pulse laser, but it does not mean that only this pulse laser can be used, and other types of pulse laser technologies should also be included in the protection scope of the present application.

[0097] The parameter settings of the XeCl excimer pulse laser in the embodiment of the present application include: the laser wavelength is 308 nm, the pulse period is 28 ns, the pulse laser energy density is 800 mJ / cm 2 , and the pulse number is 1.

[0098] It should be noted that no matter what pulse laser parameters are used for irradiation, the melting depth of the crystal material 200 should be greater than the depth of the damage layer 401 and enter the base region, so as to provide high-quality seeds for liquid-phase epitaxial regeneration of the base region.

[0099] According to the embodiment of the present application, when the substrate surface is deposited with the cover layer 202, the barrier effect of the cover layer 202 can not only effectively inhibit the diffusion of impurity atoms in the molten liquid layer and the high-temperature evaporation effect, but also can reduce the risk of ablation of the crystal surface caused by pulse laser annealing. When the cover layer 202 is too thin (<10 nm), the above barrier effect will be reduced, and when the cover layer 202 is too thick (>50 nm), it will cause a strong heat shielding effect, which is not conducive to the heating and melting of the substrate damage layer. Therefore, for different substrate conditions and pulse laser annealing conditions, the suitable thickness of the cover layer is 10 nm to 50 nm, and preferably 20 nm.

[0100] Operation S430, etching the cover layer 202 on the surface of the crystal material 200 to expose the recrystallized layer 204.

[0101] The plasma etching method or the chemical wet etching method can be used to etch the cover layer 202.

[0102] In this embodiment, the chemical wet etching method is used to etch the cover layer 202, and the chemical reagent used is hydrofluoric acid (HF), and the etching time is 30 s, wherein the concentration of HF is 1% to 5%, and preferably 3%. After etching, the crystal material 200 can be ultrasonically cleaned with alcohol and deionized water for 3 minutes, respectively, to remove the residual HF solution, and then the crystal material 200 is blown dry with a nitrogen gun, to obtain a crystal material 200 containing a recrystallized layer 204, as shown in Figure 4D .

[0103] In order to more comprehensively prove that the technical scheme of the present application can effectively obtain a high-quality recrystallized layer, the crystal structure before and after pulse annealing in the embodiment of the present application is observed, for example, the transmission electron microscope can be used to characterize the cross-sectional structure of the crystal material, and the results are as shown inFigures 5A-5C The surface damage layer is shown.

[0104] Figure 5A The transmission electron microscopy characterization results of the surface lattice damage layer caused by Ar ion implantation of the substrate germanium material in the embodiment of the present application are schematically shown.

[0105] According to the embodiment of the present application, under the plasma immersion ion implantation conditions adopted in the embodiment, the germanium layer of about 12 nm in thickness on the surface of the crystalline germanium material has been completely amorphized, but the lattice arrangement of the single crystal substrate region below the amorphous layer is still good, and there is a clear and distinct amorphous / single crystal interface layer between the two, which is conducive to realizing high-quality liquid phase epitaxial crystallization.

[0106] Figure 5B The high-resolution transmission electron microscopy characterization results of the lattice damage layer after pulsed laser irradiation in the embodiment of the present application are schematically shown.

[0107] According to the embodiment of the present application, the single crystal / amorphous interface on the surface of the substrate material disappears after the amorphous germanium layer is irradiated with the pulsed laser parameters in the embodiment, and the lattice defects and damage layer structure in the surface range of 12 nm are effectively restored, which means that the amorphous germanium layer formed by Ar ion implantation realizes high-quality liquid phase epitaxial crystallization under the action of pulsed laser irradiation.

[0108] The pulsed laser annealing parameters required for high-quality crystallization of substrate surface damage layers of different structures and depths are different. Generally, the more complete the amorphization of the substrate material, the stronger the absorption coefficient of the material, and the lower the required laser energy density. The deeper the surface damage layer, the higher the requirement for thermal penetration of the laser, and the higher the required laser energy density. It should be noted that too high laser energy density will increase the risk of ablation of the substrate surface. Therefore, the melting depth slightly greater than the surface damage layer and entering the single crystal substrate region can ensure that the liquid phase layer has a fixed crystal direction seed to realize high-quality liquid phase epitaxial crystallization.

[0109] In addition, according to the embodiment of the present application, when a substrate damage layer surface is deposited with a covering layer of appropriate thickness, the risk of surface ablation of the substrate will also be reduced, which is conducive to further expanding the energy density window of the pulsed laser.

[0110] According to the embodiment of the present application, in order to judge the change information of the content of the doping atoms before and after pulsed laser annealing, the secondary ion mass spectrometer (SIMS) can be used to detect the distribution of the doping atoms of the ion implantation damage layer before annealing and the recrystallized layer after annealing, and the effective implantation dose is calculated by numerically integrating the distribution curve in the depth direction, so as to judge the change of the content of the impurity atoms before and after annealing.

[0111] The SIMS test results of Ar atomic distribution on the surface damaged layer of the crystalline germanium material in the embodiment of the present invention before and after pulsed laser annealing are as follows: Figure 5C shown.

[0112] Figure 5C Schematically shows the SIMS test results of Ar atomic distribution on the surface damaged layer of the crystalline germanium material in an embodiment of the present invention before and after pulsed laser annealing;

[0113] According to an embodiment of the present invention, numerical integration of SIMS test curves reveals that when there is no covering layer on the crystal surface, the Ar atomic content after pulsed laser annealing is approximately 16.4% of the content before annealing. When a covering layer is deposited on the crystal surface, the Ar atomic content after pulsed laser annealing is approximately 98.6% of the content before annealing. The barrier effect of the surface covering layer can effectively reduce the diffusion and evaporation loss of Ar atoms during liquid phase epitaxial crystallization.

[0114] According to the theory of liquid-phase epitaxial doping crystallization, the content of impurity atoms captured and activated by the crystallization interface is related to the migration rate of the solidification interface and the diffusion rate of impurity atoms in the liquid phase. Increasing the migration rate of the solidification interface or reducing the impurity diffusion rate helps increase the probability of impurity activation. The present invention deposits a capping layer of appropriate thickness on the surface of the lattice-damaged substrate material before pulsed laser annealing. The physical barrier effect of the capping layer can effectively inhibit the diffusion rate of impurity atoms and effectively block the outward diffusion of impurity atoms in the molten layer caused by the crystallization front, thereby forming a molten layer with a high concentration of dopant atoms near the capping layer. The dopant atom-enriched layer near the surface causes the impurity atoms to form a concentration gradient from the outside to the inside. This concentration gradient forces the diffusion rate of impurities to drop significantly, significantly increasing the probability of impurity atoms being captured by the solidification interface, thereby reducing impurity loss during pulsed laser annealing, increasing the supersaturated doping concentration, and obtaining high-quality recrystallization. In addition, the physical barrier of the capping layer can effectively alleviate the surface evaporation of the high-temperature liquid phase layer, reducing the evaporation loss of some impurity atoms.

[0115] Therefore, the recrystallization method provided by the present invention can effectively reduce the problem of dopant atom loss caused by pulsed laser annealing. In the present invention, the surface coating layer can be deposited using semiconductor thin film preparation techniques compatible with silicon CMOS processes, such as chemical vapor deposition, magnetron sputtering, or atomic layer deposition, and can be widely used in the existing semiconductor technology industry.

[0116] The specific embodiments described above further illustrate the technical solutions of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A recrystallization method for a crystal material damaged by inert gas injection, comprising: depositing a layer of silicon dioxide or silicon nitride or aluminum oxide with a thickness of 10 nm-50 nm on a surface of the crystal material to form a cover layer; the cover layer is used to inhibit the diffusion escape phenomenon of bubbles and to alleviate the surface evaporation effect of a high-temperature molten layer; irradiating one side of the crystal material on which the cover layer is deposited with a pulsed laser to heat and cool the crystal material to crystallize, thereby forming a recrystallization layer on a side of the crystal material close to the cover layer; wherein when the one side of the crystal material on which the cover layer is deposited is irradiated with the pulsed laser, the melting depth of the crystal material is greater than the depth of a bubble layer or a crystal lattice damage layer by adjusting the parameters of the pulsed laser; the bubble layer is formed by injecting inert gas into the crystal material; etching away the cover layer on the surface of the crystal material to expose the recrystallization layer.

2. The method of claim 1, wherein, The cover layer is deposited by a chemical vapor deposition method or a reactive magnetron sputtering method or an atomic layer deposition method.

3. The method of claim 2, wherein, The chemical vapor deposition method includes a plasma-enhanced chemical vapor deposition method or a low-pressure chemical vapor deposition method.

4. The method of claim 1, wherein, When the one side of the crystal material on which the cover layer is deposited is irradiated with the pulsed laser, the period of the pulsed laser can be set to nanoseconds, picoseconds or femtoseconds.

5. The method of claim 1, wherein, The cover layer is etched by a plasma etching method or a chemical wet etching method.

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