CN116913768A - Multiple pulse sub-melting excimer laser annealing method - Google Patents

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a multi-pulse sub-melting excimer laser annealing method, which comprises the following steps: ion implantation is carried out on the surface of the semiconductor crystal, and an amorphous doping area is formed on the surface of the semiconductor crystal; and carrying out pulse laser irradiation annealing for a plurality of times on the amorphous doped region so as to enable the amorphous doped region to be recrystallized in a sub-melting state and activate ions of the amorphous doped region. Meanwhile, the impurity segregation effect caused by surface ablation, evaporation effect and melt cooling regeneration is avoided, so that the doping atom loss in the recrystallization process is greatly reduced.

Description

Multiple pulse sub-melting excimer laser annealing method

Technical field

The invention belongs to the field of semiconductor technology, and specifically relates to a multi-pulse sub-melting excimer laser annealing method.

Background technique

With the rapid development of semiconductor devices, the requirements for their performance are getting higher and higher, which puts forward more special requirements for their processing technology. For example, due to the continuous shrinkage of semiconductor chip feature sizes, the source and drain regions of transistors require lower resistance and ultra-shallow junctions (USJ) to reduce the short channel effect, that is, the doping depth becomes shallower and shallower, and the doping depth becomes shallower and shallower. The impurity concentration is getting higher and higher. The method of forming shallow junctions by reducing the implanted ion energy has always attracted attention in this field. At the same time, the preparation of highly activated USJ has become one of the biggest challenges in modern doping processes, which requires extremely low ion implantation energy and ultra-high doping concentration. .

In the related art, in order to form a highly activated shallow junction profile, low-energy beam ion implantation technology and immersion plasma implantation technology are widely used in semiconductor wafers to introduce dopants. After the implantation is completed, methods such as flash lamp annealing (FLA) and spike rapid thermal annealing (spike-RTA) are used to eliminate implant damage and activate dopants. However, due to the long annealing time and limited impurity activation, FLA and spike-RTA are not suitable for forming ultra-shallow junctions with high activation levels.

In the field of semiconductors, research on silicon-based high-efficiency luminescent materials and devices is one of the hot spots. In the existing technology, a direct bandgap silicon-based luminescent material preparation method compatible with the silicon CMOS process has been proposed, using ion implantation technology to implant germanium in the crystal. Inert atoms with a concentration of more than 1% are introduced to cause the lattice expansion to produce equivalent tensile strain, thereby realizing the conversion of the indirect band gap to the direct band gap, thereby achieving efficient light emission. In addition, direct band gap luminescence can also be achieved by placing a specific concentration of germanium or tin atoms into germanium to form split [110] interstitial sites and other electron doping. However, regardless of whether the closed-shell layer is doped with inert gas atoms or isoelectronic germanium atoms and tin atoms, the equilibrium solid solubility in single crystal germanium is far less than 1%. It is difficult to repair the lattice damage caused by doping. This will cause a large number of dopant atoms to escape from the surface.

Single-pulse excimer laser annealing (ELA) technology can recrystallize damaged semiconductor materials and activate impurities. Its nanosecond-level annealing cycle can significantly shorten the annealing time and increase the annealing temperature, so it has higher impurity activation efficiency. At the same time, its effective annealing depth can be precisely controlled by the laser energy density. Therefore, single-pulse excimer laser annealing technology has great application potential in the preparation of low-resistance ultra-shallow junctions.

However, further research found that single-irradiation single-pulse excimer laser annealing usually requires higher laser energy density to activate the dopants. This puts the surface of the material matrix in a molten state, and a high-quality regeneration layer is obtained through the liquid phase epitaxial crystallization mechanism during the rapid cooling process. Its high-temperature melting-cooling crystallization mechanism has its inherent flaws: on the one hand, the molten doped layer solidifies and crystallizes rapidly. It will cause fluctuations in the surface of the substrate, resulting in roughening or unevenness of the surface of the regenerated substrate, which is not conducive to device preparation. On the other hand, dopants will be redistributed in the melt and partially lost during rapid cooling and crystallization, thus facing serious doping atom loss problems when using single-pulse excimer laser annealing technology for annealing.

Therefore, proposing an annealing technology is of far-reaching significance in the preparation of ultra-shallow junctions with low resistance and high activation and direct band gap silicon-based luminescent materials.

Contents of the invention

In view of this, in order to solve at least one technical problem in the related art and other aspects, the present invention proposes a multi-pulse sub-melting excimer laser annealing method, which includes: ion implantation on the surface of the semiconductor crystal; An amorphous doped area is formed on the surface; multiple pulse laser irradiation and annealing are performed on the amorphous doped area, so that the amorphous doped area recrystallizes in a sub-melted state and activates ions in the amorphous doped area.

According to embodiments of the present invention, the recrystallization process is performed layer by layer in a solid-phase epitaxial crystallization manner from the crystalline region to the amorphous doped region.

According to embodiments of the present invention, the energy density of pulsed laser irradiation is 80% to 95% of the melting threshold of the semiconductor crystal.

According to an embodiment of the present invention, the frequency of pulsed laser irradiation is less than 20 Hz.

According to an embodiment of the present invention, the pulse laser includes one of an excimer nanosecond pulse laser, a femtosecond pulse laser, and a millisecond pulse laser.

According to embodiments of the present invention, during the recrystallization process, the energy density of pulsed laser irradiation is gradually increased to compensate for the impact of changes in reflectivity and heat absorption coefficient of the amorphous doped region on the recrystallization rate.

According to embodiments of the present invention, the semiconductor crystal includes one of elemental semiconductors and compound semiconductors, preferably one of silicon, germanium, silicon carbide, and gallium nitride.

According to embodiments of the present invention, the semiconductor crystal structure type includes a bulk structure or a thin film structure.

According to embodiments of the present invention, the doping type of the amorphous doped region includes one of n -type doping, p -type doping, isoelectronic doping, and inert gas atom doping; preferably, the inert gas atom is argon. atom.

According to embodiments of the present invention, ion implantation includes a beam line ion implantation method or a plasma immersion ion implantation method.

According to embodiments of the present invention, the thickness of the amorphous doped region is less than 300 nm.

According to embodiments of the present invention, the multi-pulse sub-melting excimer laser annealing method allows the amorphous doped region where ions are implanted to always maintain a solid phase state during the recrystallization process, and the extremely low diffusion rate in the solid phase makes the ion implantation distribution It is basically not affected by thermal annealing, and avoids surface ablation, evaporation effects and impurity segregation effects caused by melt cooling and regeneration, greatly reducing the loss of doping atoms during the recrystallization process. At the same time, because the amorphous doped region is in a sub-melting state, there is no substrate surface undulation and roughening caused by melting fluctuations during the liquid phase epitaxial crystallization process. After recrystallization, a flat morphology similar to the initial injection surface can be obtained. .

Description of the drawings

Figure 1 is a flow chart of a multi-pulse sub-melting excimer laser annealing method in an embodiment of the present invention;

Figure 2 is a schematic diagram of the recrystallization method of the multi-pulse sub-melting excimer laser annealing method in the embodiment of the present invention;

Figure 3 is a flow chart of a multi-pulse sub-melting excimer laser annealing method for the surface of a germanium substrate after argon ion implantation in an embodiment of the present invention; (a) is a schematic diagram of the substrate, (b) is a schematic diagram of argon atom implantation, (c) ) is a schematic diagram of multiple pulse sub-melting excimer laser annealing;

Figure 4 is a high-resolution transmission electron micrograph of the germanium substrate surface after argon ion implantation in one embodiment of the present invention;

Figure 5 is a high-resolution transmission electron micrograph of the germanium substrate surface after multi-pulse sub-melting excimer pulse laser annealing in one embodiment of the present invention;

Figure 6 is a comparative curve chart of the Ar atom doping distribution of the base germanium material after single-pulse liquid-phase epitaxial crystallization and multi-pulse sub-melting solid-phase epitaxial crystallization in an embodiment of the present invention.

Reference signs

1. Base body;

2. Amorphous doped region;

3. Amorphous doping interface;

4. Multiple pulse sub-melting excimer laser.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The endpoints of ranges and any values disclosed in this disclosure are not limited to the precise range or value, but these ranges or values are to be understood to include values approximating those ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges. These values Ranges should be considered to be specifically disclosed in this disclosure.

The terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting of the invention. The terms "comprising," "comprising," and the like, as used herein, indicate the presence of stated features, steps, operations, and/or components but do not exclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted to have meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

Similarly, in the above description of exemplary embodiments of the invention, in order to streamline the invention and assist in understanding one or more of the various disclosed aspects, various features of the invention are sometimes grouped together into a single embodiment, figure, or grouped together. In description. Reference to a description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example includes In at least one embodiment or example of the invention. In this specification, schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

In the traditional laser annealing process, there are three main factors causing the loss of dopant atoms, including the surface ablation effect during high-energy laser irradiation, the surface evaporation effect during matrix melting, and the impurity segregation effect during melt cooling and regeneration. Under the combined effect of these factors, the single-pulse excimer laser annealing process significantly reduces the number of doping atoms that remain in the semiconductor matrix and are effectively activated after annealing and recrystallization.

When the semiconductor base material is irradiated with nanosecond pulse laser energy higher than its melting threshold, the surface will melt. The melting front rapidly (~10m/s) penetrates into the semiconductor base material until the irradiation ends. Subsequently, the surface molten layer solidifies and crystallizes by releasing heat to the semiconductor matrix, and the melting front quickly sweeps back to the surface. The entire process will be completed in tens of nanoseconds, which is called non-equilibrium liquid phase epitaxial crystallization. During the entire melting-crystallization process, the surface ablation effect caused by laser irradiation, the surface evaporation effect caused by high-temperature melt, and the impurity segregation effect caused by cooling and regeneration of the melt will all cause the loss of doping atoms.

In order to solve this problem, those skilled in the art have proposed depositing a dielectric protective layer of a specific thickness on the surface of the substrate before single-pulse excimer laser annealing (ELA) technology. However, follow-up studies have found that this protective layer can act as a source of impurity contamination to introduce undesirable impurities into the matrix during high-energy ELA treatment. The impurities combine with existing n -type or p -type impurities to cause a large amount of the latter. Deactivated. Therefore surface depositing a dielectric layer is not an ideal solution. Since a suitable annealing scheme has not yet been found, traditional single-pulse excimer laser annealing will not be able to play its advantageous role in the preparation of low-resistance and high-activation USJs and direct bandgap silicon-based luminescent materials, resulting in its use in cutting-edge microelectronics and optoelectronics technologies in the future. Applications in various fields are greatly restricted.

In the present invention, the amorphous doped region is continuously irradiated multiple times with pulsed laser energy slightly lower than the melting threshold to ensure that the amorphous doped region is always in the solid phase during the recrystallization process and is crystallized by solid phase epitaxy. way to achieve recrystallization growth. Due to the extremely low diffusion rate of dopant atoms in the solid state, the ion implantation distribution is basically not affected by thermal annealing. Therefore, the surface ablation effect caused by irradiation, the evaporation effect on the melt surface, and the segregation of impurities caused by cooling and regeneration The effects can be effectively suppressed.

Figure 1 is a flow chart of a multi-pulse sub-melting excimer laser annealing method in an embodiment of the present invention.

This disclosure proposes a multi-pulse sub-melting excimer laser annealing method, as shown in Figure 1, including the following steps S1 and S2.

Step S1: Perform ion implantation on the surface of the semiconductor crystal to form an amorphous doped region on the surface of the semiconductor crystal.

Step S2: Perform multiple pulse laser irradiation and annealing on the amorphous doped region, so that the amorphous doped region recrystallizes in a sub-melted state and activates ions in the amorphous doped region.

According to embodiments of the present invention, the multi-pulse sub-melting excimer laser annealing method allows the amorphous doped region where ions are implanted to always maintain a solid phase state during the recrystallization process. This extremely low diffusion rate in the solid phase form The ion implantation distribution is basically not affected by thermal annealing, and the impurity segregation effect caused by surface ablation, evaporation effects and melt cooling regeneration is avoided, greatly reducing the loss of doping atoms during the recrystallization process. At the same time, because the amorphous doped region is in a sub-melting state, there is no substrate surface undulation and roughening caused by melting fluctuations during the liquid phase epitaxial crystallization process. After recrystallization, a flat morphology similar to the initial injection surface can be obtained. .

Figure 2 is a schematic diagram of the recrystallization method of the multi-pulse sub-melting excimer laser annealing method in the embodiment of the present invention.

According to an embodiment of the present invention, as shown in FIG. 2 , as the amorphous doped region 2 recrystallizes, the amorphous doped interface 3 moves. According to the Arrhenius theoretical model, atoms at the three amorphous doping interfaces can only migrate a few atomic layers under each pulse, which means that the crystallization depth that each pulse can trigger is approximately several atomic layers. Therefore, in order to completely complete the recrystallization of the entire doped layer, the substrate needs to be irradiated with multiple pulses continuously in the sub-melting crystallization mode.

According to embodiments of the present invention, the recrystallization thickness can be controlled by changing the number of pulses.

According to an embodiment of the present invention, the recrystallization process is performed layer by layer in a solid-phase epitaxial crystallization manner from the crystalline region to the amorphous doped region 2 .

According to the embodiment of the present invention, under the action of multiple pulse sub-melting excimer laser annealing, the recrystallization direction of the amorphous doped region moves from the crystal region to the amorphous doped region 2, that is, the amorphous doped interface 3 changes from the crystalline region to the amorphous doped region 2. The region moves toward the amorphous doped region 2. The recrystallization thickness is precisely controlled by the number of pulses to achieve a buried-layer crystallization effect, which can meet the crystallization needs of specific fields.

According to embodiments of the present invention, when the amorphous doped region is irradiated with pulse laser energy lower than the melting threshold, its surface rapidly heats up to a sub-melting state. After each pulse, the amorphous doped region passes toward the bottom. The matrix releases heat and cools, so the recrystallization direction is from bottom to top (that is, moving from the crystalline region to the amorphous doped region).

According to embodiments of the present invention, the energy density of pulsed laser irradiation is 80% to 95% of the melting threshold of the semiconductor crystal, for example, it can be 80%, 83%, 85%, 90%, 93%, etc., preferably 90%.

According to embodiments of the present invention, the pulse laser energy density should be slightly lower than the melting threshold of the amorphous doped region, so that the amorphous doped region is always in a sub-melted state under irradiation. The more complete the amorphization of the amorphous doped region, the higher the defect content, the stronger the corresponding heat absorption coefficient, and the lower the required laser energy density will be. In addition, the deeper the amorphous doped region, the higher the thermal penetration requirements of the laser, and the higher the required laser energy density. Therefore, for a specific matrix material, the optimized laser energy density depends on the implantation layer depth and defect content.

According to embodiments of the present invention, the frequency of pulsed laser irradiation is less than 20 Hz, for example, it can be selected as 5 Hz, 8 Hz, 10 Hz, 13 Hz, 16 Hz, 18 Hz, etc.

According to embodiments of the present invention, during the multi-pulse sub-melting excimer laser annealing process, the effect of each pulse on the substrate should be independent, that is, each pulse should not affect each other. However, due to the limited thermal diffusion efficiency of the substrate, the heat accumulation effect of multi-pulse irradiation may cause surface melting of the substrate, so the pulse frequency should not be too high. On the other hand, in order to shorten the annealing time and meet the needs of industrial applications, the laser irradiation frequency cannot be too low. After comprehensively considering the surface thermal effect and annealing time cost, the incident frequency set in the present invention should generally be less than 20 Hz. The specific value depends on factors such as the type of base material, the degree of injection damage, and the incident laser parameters.

According to embodiments of the present invention, the number of pulses of the multi-pulse sub-melting excimer laser annealing should be able to completely crystallize the amorphous doped region.

According to an embodiment of the present invention, the pulse laser includes one of an excimer nanosecond pulse laser, a femtosecond pulse laser, and a millisecond pulse laser.

According to embodiments of the present invention, the multi-pulse sub-melting excimer laser annealing method proposed by the present invention essentially belongs to solid-phase epitaxial crystallization, but the ultra-fast heating and cooling rates caused by nanosecond pulses make it possess non-equilibrium doping characteristics.

According to embodiments of the present invention, during the recrystallization process, the energy density of pulsed laser irradiation is gradually increased to compensate for the impact of changes in reflectivity and heat absorption coefficient of the amorphous doped region on the recrystallization rate.

According to embodiments of the present invention, as the recrystallization process continues, the residual depth of the amorphous doped region will continue to become thinner, and the reflectivity of the substrate surface to the incident laser and its heat absorption coefficient will also continue to change. When the laser irradiation energy This change will slightly reduce the crystallization rate. Therefore, in order to obtain a uniform recrystallization rate and facilitate precise control of the recrystallization thickness, the laser irradiation energy density can be gradually increased during the annealing process to compensate for the impact of changes in reflectivity and heat absorption coefficient on the recrystallization rate.

According to embodiments of the present invention, the semiconductor crystal includes one of elemental semiconductors and compound semiconductors, preferably one of silicon, germanium, silicon carbide, and gallium nitride.

According to embodiments of the present invention, semiconductor crystal structure types include bulk structures or thin film structures, where the thin film structures include but are not limited to SOI (Silicon-On-Insulator) or GOI (Germanium-On-Insulator).

According to embodiments of the present invention, the doping type of the amorphous doping region includes one of n-type doping, p-type doping, isoelectronic doping, and inert gas atomic doping; preferably, when applied to silicon-based When using a light-emitting device, the inert gas atoms may be argon atoms.

According to embodiments of the present invention, in order to prevent inert atom implantation from forming a bubble structure in the matrix and hindering subsequent annealing and crystallization, the inert atom implantation dose generally needs to be less than 5×10 ¹⁶ /cm ² .

According to embodiments of the present invention, ion implantation includes a beam line ion implantation method or a plasma immersion ion implantation method.

According to embodiments of the present invention, the thickness of the amorphous doped region is less than 300 nm.

According to embodiments of the present invention, in order to quickly determine whether the amorphous doped region has been completely recrystallized after multiple-pulse sub-melting excimer laser annealing in the industrial line, online non-destructive Raman ( (Raman), The change in intensity is used to determine whether high-quality epitaxial crystallization is achieved.

It should be noted that the described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

Example:

In this embodiment, a multi-pulse sub-melting excimer laser annealing method of an amorphous matrix germanium material doped with inert atoms Ar is schematically illustrated.

Figure 3 is a flow chart of a method for multiple pulse sub-melting excimer laser annealing of the germanium substrate surface after argon ion implantation in one embodiment of the present invention.

Step S101: Prepare semiconductor bulk germanium as the substrate 1, as shown in (a) in Figure 3. Among them, the size of the substrate 1 is 2 inches, the resistance is 0.01-0.05Ω·cm, the crystal phase is <110>, and the melting threshold of completely amorphous germanium is about 350mJ/cm ² .

Step S102: Carry out inert atomic Ar implantation on one side of the substrate 1 to form a layer of Ar atom amorphous doping region 2 with a specific depth, as shown in (b) in Figure 3 . Among them, immersion plasma ion implantation technology is used to inject Ar atoms into the substrate 1, the injection energy is 5kV, the injection dose is 1×10 ¹⁶ /cm ² , the working pressure of the Ar gas in the cavity during the injection is 10 ^-3 Pa, and the discharge The power is 500W, the rectangular voltage pulse width used for discharge is 10μs, and the pulse frequency is 1kHz.

Figure 4 is a high-resolution transmission electron micrograph of the surface of a germanium substrate after argon ion implantation in an embodiment of the present invention.

As shown in Figure 4, the depth of about 15 nm on the surface of substrate 1 has been completely amorphous, and the underlying lattice in contact with it is still well arranged, with a clear transition interface between the two.

Step S103: Use an excimer nanosecond pulse laser to perform multi-pulse sub-melting irradiation on the amorphous doped region 2. The amorphous doped interface 3 moves from bottom to top to completely recrystallize it, as shown in (c in Figure 3 ) shown. Among them, the XeCl excimer nanosecond pulse laser annealing system is equipped with a beam homogenizer, the beam cross-section size is 5mm×5mm, and the energy distribution is uniform. The wavelength of the XeCl excimer nanosecond pulse laser is 308nm, the pulse period is 28ns, the laser energy density used is 300mJ/cm ² , the pulse frequency is 8Hz, and the number of pulses is 500.

Figure 5 is a high-resolution transmission electron micrograph of the germanium substrate surface after multi-pulse sub-melting excimer pulse laser annealing in one embodiment of the present invention.

As shown in Figure 5, after multi-pulse sub-melting laser irradiation treatment, the amorphous doped area on the germanium surface of substrate 1 completely disappeared, and the germanium lattice arrangement was effectively restored without residual lattice defects, which means that the amorphous doped area The impurity region achieves high-quality epitaxial crystallization under the action of sub-melting multi-pulse laser annealing.

In order to confirm the Ar atom doping content distribution in the matrix before and after using the multiple pulse sub-melting excimer laser annealing method in this example, a secondary ion mass spectrometer (SIMS) was used to analyze the doping elements.

For comparison, single-pulse high-energy excimer nanosecond pulse laser annealing was used to perform liquid-phase epitaxial crystallization of ion-implanted samples. The laser energy density was 800mJ/cm ² . Under this pulse laser irradiation condition, the amorphous doped region is completely melted. After the irradiation is completed, the molten layer uses the single crystal matrix as the seed crystal to achieve liquid phase epitaxial regeneration. The Ar atom doping distribution after liquid phase epitaxial crystallization was also analyzed using SIMS technology, and the results are shown in Figure 6.

Figure 6 is a comparative curve chart of the Ar atom doping distribution of the base germanium material after single-pulse liquid-phase epitaxial crystallization and multi-pulse sub-melting solid-phase epitaxial crystallization in an embodiment of the present invention.

As shown in Figure 6, the Ar atom content in the matrix dropped significantly after high-energy single-pulse liquid-phase epitaxial crystallization, especially in the region close to the doped surface. However, for solid-phase epitaxial crystallization induced by multi-pulse sub-melting mode, the doping loss phenomenon is greatly suppressed, especially in the surface high-concentration amorphous doped region, where the Ar content loss is even lower.

As mentioned before, this is related to the low diffusion rate of inert atoms in the solid phase matrix and the ultra-high crystallization rate. That is, in the multi-pulse ultrafast solid-phase epitaxial crystallization process, a large number of Ar atoms in the amorphous layer do not have enough time. Escape from the matrix is captured by the crystallographic interface moving from bottom to top. Compared with inert gas atoms, conventional n -type , p -type or isoelectronic doping atoms can stably form bonds with the matrix, and can be captured by the regenerated matrix during the recrystallization process and enter the lattice substitution site.

Therefore, the multi-pulse sub-melting mode crystallization for this type of doped atoms can further reduce the loss of impurities, which is beneficial to achieving ultra-high solid solubility doping.

In the present invention, both the ion implantation technology and the multi-pulse sub-melting laser annealing technology are compatible with the CMOS process and can be used on a large scale in the existing semiconductor technology industry. Therefore, this new annealing technology will become the future preparation method for low-resistance USJ and new direct tape. A favorable solution for gap-emitting silicon-based materials.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent substitutions, improvements, etc. shall be included in the protection scope of the present invention.

Claims (12)

1. A multiple pulse sub-melt excimer laser annealing method, comprising:

ion implantation is carried out on the surface of the semiconductor crystal, and an amorphous doping area is formed on the surface of the semiconductor crystal;

and carrying out pulse laser irradiation annealing for a plurality of times on the amorphous doped region so as to enable the amorphous doped region to be recrystallized in a sub-melting state and activate ions of the amorphous doped region.

2. The multiple pulse sub-fusion excimer laser annealing process of claim 1, wherein the recrystallization process is a layer-by-layer recrystallization from a crystalline region to the amorphous doped region in a solid phase epitaxial crystallization.

3. The multiple pulse sub-melting excimer laser annealing process of claim 1, wherein the energy density of the pulsed laser irradiation is 80% to 95% of the melting threshold of the semiconductor crystal; the frequency of the pulsed laser irradiation is less than 20Hz.

4. The multiple pulse sub-melt excimer laser annealing method of claim 1, wherein the pulsed laser comprises one of an excimer nanosecond pulsed laser, a femtosecond pulsed laser, and a millisecond pulsed laser.

5. The multiple pulse sub-fusion excimer laser annealing process of any one of claims 1-4, wherein during the recrystallization process, the energy density of the pulsed laser irradiation is gradually increased to compensate for the effect of the amorphous doped region reflectivity and thermal absorption coefficient variations on the recrystallization rate.

6. The multiple pulse sub-fusion excimer laser annealing method of claim 1, wherein the semiconductor crystal comprises one of an elemental semiconductor and a compound semiconductor.

7. The multiple pulse sub-melt excimer laser annealing process of claim 6, wherein the semiconductor crystal comprises one of silicon, germanium, silicon carbide, gallium nitride.

8. The multiple pulse sub-melt excimer laser annealing process of claim 1, wherein the semiconductor crystal structure type comprises a bulk structure or a thin film structure.

9. The multiple pulse sub-melt excimer laser annealing process of claim 1, wherein the doping type of the amorphous doped region comprises one of n-type doping, p-type doping, isoelectron doping, and inert gas atomic doping.

10. The multiple pulse sub-fusion excimer laser annealing process of claim 9, wherein the inert gas atoms doping the amorphous doped regions are argon atoms.

11. The multiple pulse sub-fusion excimer laser annealing process of claim 1, wherein the ion implantation comprises a beam-line ion implantation process or a plasma immersion ion implantation process.

12. The multiple pulse sub-melt excimer laser annealing process of claim 1, wherein the amorphous doped region has a thickness of less than 300nm.