JP2016076686A - Laser annealing method of semiconductor wafer using localization control of ambient oxygen gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the oxidation amount during laser annealing, by performing laser annealing of a semiconductor wafer using the forming gas for localization control of ambient oxygen gas.SOLUTION: Forming gas 202 contains hydrogen gas, and an inactive buffer gas such as nitrogen gas. Local heating of oxygen gas 205 and forming gas in the vicinity of annealing position 55 on the semiconductor wafer 50 surface forms a local region, where combustion of oxygen gas and hydrogen gas is caused and steam is generated. The combustion reaction reduces oxygen gas concentration in the local region. Consequently, the amount of ambient oxygen gas is reduced locally, thus reducing oxidation speed on the semiconductor wafer surface while annealing.SELECTED DRAWING: Figure 3B

Description

  The present disclosure relates to laser annealing, and in particular, to a laser annealing method using localized oxygen gas localization control.

  The entire disclosure of any publication or patent document mentioned in this specification is hereby incorporated by reference. Publications or patent documents include US Pat. No. 5,997,963 (hereinafter referred to as the '963 patent), US Pat. No. 6,747,245; US Pat. No. 7,098,155; US Patent No. 7,157,660; US Patent No. 7,763,828; US Patent No. 8,309,474 and US Patent No. 9,029,809.

  Laser annealing (also called laser spike annealing, laser thermal annealing, laser heat treatment, etc.) is used for various applications in semiconductor manufacturing. Various applications also include activating dopants in selected regions of equipment (structures) formed on a semiconductor wafer when forming active microcircuits such as transistors and related types of semiconductor features.

  The laser annealing process is typically performed under vacuum in a processing chamber (or reaction chamber) such as, for example, a microchamber described in the '344 publication and the' 963 patent. One reason for using a vacuum is to reduce the amount of oxygen gas present on the surface of the semiconductor wafer being processed. This is because oxygen gas is highly reactive and oxidizes the semiconductor wafer surface. This is especially true in the case of laser annealing at high temperatures, since the oxidation rate increases with increasing temperature.

  Under normal vacuum conditions, the oxygen gas concentration inside the processing chamber can be reduced to about 50 parts per million (ppm) (vol.). Further reducing the oxygen gas concentration is problematic and requires not only substantial improvements in the processing chamber, but also expensive equipment (eg, more powerful vacuum pumps).

  Therefore, it is desirable to reduce the amount of oxygen gas on the surface of the semiconductor wafer to be laser annealed in a low cost and simple manner beyond what is possible with a conventional vacuum approach.

One aspect of the present disclosure is a method of laser annealing a semiconductor wafer having a surface. The method includes positioning a semiconductor wafer within the processing chamber, pulling the inside of the processing chamber to the vacuum, the process chamber interior, and be made to contain O ₂ by initial O ₂ concentration, H ₂ and buffer Introducing a forming gas containing a gas into the processing chamber; passing a laser beam into the processing chamber; and causing the laser beam to enter an annealing position on the surface of the semiconductor wafer. In the local region around the annealing position, where O ₂ and H ₂ are combusted to generate H ₂ O vapor, O ₂ and H ₂ of the forming gas are locally heated. This comprises reducing the O ₂ concentration in the local region compared to the initial O ₂ concentration.

Another aspect of the present disclosure is the above-described method, wherein the forming gas preferably includes 5 volume (vol)% H ₂ and 95 volume (vol)% N ₂ .

Another aspect of the present disclosure is in the aforementioned method, the local region, are preferably defined by a combustion temperature T _C in the range of 500 ° C. from 100 ° C..

  Another aspect of the present disclosure is the method described above, wherein the processing chamber is preferably a microchamber.

  Another aspect of the present disclosure is the above method, further comprising moving the semiconductor wafer relative to the laser beam, whereby the annealing position moves relative to a surface of the semiconductor wafer. Preferably, it is in a fixed position relative to its initial position inside the processing chamber.

Another aspect of the present disclosure is the above-described method, wherein the initial O ₂ concentration is preferably 50 ppm (vol.) Or more. The reduced O ₂ concentration is preferably 10 ppm (vol.) Or less.

Another aspect of the present disclosure is in the aforementioned method, the semiconductor wafer preferably has a melting temperature T _M. Annealing of the surface of the semiconductor wafer is preferably carried out at an annealing temperature T _A. Here _is a _T A <T _M.

  Another aspect is a method for reducing oxygen gas in a local region around an annealing position during annealing of a semiconductor wafer having a surface. The method includes introducing a forming gas containing hydrogen gas and a buffer gas into the processing chamber containing the semiconductor wafer and the initial concentration of the oxygen gas, and laser annealing the surface of the semiconductor wafer, thereby In the local region around the annealing position, where the oxygen gas and the hydrogen gas burn and the water vapor is generated, the oxygen gas and the hydrogen gas of the forming gas are locally heated, thereby Reducing the oxygen gas concentration in the local region compared to the initial oxygen gas concentration.

  Another aspect of the present disclosure is the above-described method, wherein the buffer gas preferably includes 5% (vol)% hydrogen gas and 95% (vol)% nitrogen gas.

Another aspect of the present disclosure is in the aforementioned method, the local region, are preferably defined by a combustion temperature T _C in the range of 500 ° C. from 100 ° C..

  Another aspect of the present disclosure is the method described above, wherein the processing chamber is preferably a microchamber.

  Another aspect of the present disclosure is the method described above, wherein the processing chamber preferably has a pressure less than atmospheric pressure.

  Another aspect of the present disclosure is the above method, further comprising moving the semiconductor wafer relative to the laser beam, whereby the annealing position moves relative to a surface of the semiconductor wafer. Preferably, it is in a fixed position relative to its initial position inside the processing chamber.

  Another aspect of the present disclosure is the method described above, wherein the initial concentration of the oxygen gas is preferably 50 ppm (vol.) Or more. The reduced oxygen concentration is preferably 10 ppm (vol.) Or less.

Another aspect of the present disclosure is in the aforementioned method, the semiconductor wafer preferably has a melting temperature T _M. Annealing of the surface of the semiconductor wafer is preferably carried out at an annealing temperature T _A. Here _is a _T A <T _M.

Another aspect of the present disclosure is a method of laser annealing a semiconductor wafer having a surface. In this method, a semiconductor wafer is disposed inside a processing chamber containing O ₂ at an initial O ₂ concentration, a forming gas containing H ₂ and a buffer gas is introduced into the processing chamber, and a laser is introduced into the processing chamber. A laser beam is incident on an annealing position on the surface of the semiconductor wafer, thereby annealing the surface of the semiconductor wafer, and a local region around the annealing position, wherein O ₂ and H ₂ In a local region where combustion occurs and generates H ₂ O vapor, O ₂ and the H ₂ of the forming gas are locally heated, thereby reducing the O ₂ concentration in the local region compared to the initial O ₂ concentration. Providing.

Another aspect of the present disclosure is the above-described method, preferably further including drawing a vacuum after the semiconductor wafer is disposed inside the processing chamber. The initial O ₂ concentration is defined by the amount of O ₂ remaining (concentration) remaining in the processing chamber after the vacuum is pulled.

Another aspect of the present disclosure is the above-described method, wherein the initial O ₂ concentration is preferably 50 ppm (vol.) Or more. The reduced O ₂ concentration is preferably 10 ppm (vol.) Or less.

  Another aspect of the present disclosure is the method described above, wherein the processing chamber is preferably a microchamber.

  Another aspect of the present disclosure is the above-described method, wherein the buffer gas preferably includes 5% (vol)% hydrogen gas and 95% (vol)% nitrogen gas.

  Additional features and advantages are specified in the detailed description below. Some of them will be readily apparent to those skilled in the art from the description in the detailed description, or may be recognized by implementing the embodiments described in the detailed description, the claims, and the accompanying drawings. Let's go. It is to be understood that the foregoing summary and the following detailed description are exemplary only and provide a general outline or framework for understanding the nature and features of the present invention as set forth in the claims. Should be understood.

The accompanying drawings are included to provide a further understanding, and constitute a part of this specification and are incorporated into this specification. The drawings illustrate one or more embodiments, and together with the detailed description serve to explain the principles and operations of the various embodiments. Thus, the present disclosure will become more fully understood from the detailed description set forth below when taken in conjunction with the accompanying drawings.
FIG. 1A is an (XZ plane) of an example embodiment of a processing chamber system suitable for use in performing the annealing method and ambient oxygen gas (O ₂ ) localization control method disclosed herein. FIG. FIG. 1B is an exploded view of several major components of the processing chamber system of FIG. 1A. FIG. 1C is a top view (in the XY plane) showing the processing chamber system of FIG. 1A, along with line 1-1 showing the cross section of FIG. 1A. FIG. 2 is a simplified diagram of the processing chamber system of FIG. 1A illustrating an example annealing method that includes the formation of local regions using forming gas to perform localization control of ambient oxygen gas. is there. FIG. 3A is an enlarged view of the surface of the semiconductor wafer inside the processing chamber after introduction of the forming gas, and shows how the forming gas and oxygen gas are normally distributed uniformly on the surface of the semiconductor wafer prior to laser annealing. FIG. FIG. 3B is an enlarged view of a local region generated during the laser annealing process and surrounding the annealing position on the semiconductor wafer surface. In this laser annealing process, the oxygen gas concentration in the local region becomes lower than the oxygen gas concentration in other parts inside the processing chamber due to a decrease in the oxygen gas amount (concentration) in the local region.

  Hereinafter, various embodiments of the present disclosure and examples shown in the accompanying drawings will be described in detail. Wherever possible, the same or similar reference numbers and reference numerals are used in the drawings of the same or similar parts. The drawings are not to scale and those skilled in the art will recognize that the drawings have been simplified to illustrate the major portions of the present invention.

  The following claims are hereby incorporated into and constitute a part of the detailed description of the invention.

  The entire disclosure of any publication or patent document mentioned in this specification is incorporated by reference.

  In some of the drawings, Cartesian coordinates are drawn for reference, but this does not limit the orientation and location.

In the following description, the term “evacuating” or the term “vacuum” related to the inside of the processing chamber means reducing the pressure inside the processing chamber to below ambient pressure or atmospheric pressure outside the processing chamber. However, it does not necessarily mean that all atoms are removed (evacuated) from the inside of the processing chamber. Exemplary methods disclosed herein include evacuating the process chamber and / or evacuating the process chamber. In this method, the initial concentration C _{OX of} oxygen gas remains in the processing chamber. Here, the term “initial concentration” means that the method of performing localized control of the oxygen gas volume in the processing chamber starts with this concentration and ends with a reduced concentration compared to the initial concentration C _OX. Used to mean implemented.

  The terms “processing” and “method” are used interchangeably herein.

The expression “localized oxygen gas localization control” is understood to mean that the oxygen gas amount (concentration) decreases locally with respect to the initial amount (concentration) of oxygen gas.
<Processing chamber system>

  FIG. 1A is a schematic cross-sectional view (in the XZ plane) of an example embodiment of a processing chamber system (“system”) 10 suitable for use in performing the methods disclosed herein. FIG. 1B is an exploded view of some major components of the system 10 of FIG. 1A. FIG. 2C is a top view (in the XY plane) showing the system 10 of FIG. 1A, along with line 1-1 indicating the cross section of FIG. 1A. 1A to 1C represent one type of processing chamber derived from the '344 publication and called a “microchamber”.

  The system 10 has a Z-center line CZ extending in the Z direction and an X-center line CX extending in the X direction. The system 10 resides in an ambient environment 8 that can include at least one reactive gas, such as oxygen gas. The ambient environment 8 may also include a non-reactive gas such as neon gas or argon gas, or a stable gas such as nitrogen gas.

  System 10 includes an upper end member 20. The upper end member 20 has an upper surface 22, a lower surface 24, and an outer edge portion 26. In one example, the upper end member 20 is substantially rectangular and has a parallel upper surface 22 and lower surface 24. In one example, the upper end member 20 is cooled, as will be described in more detail below. In one example, the upper end member 20 includes at least one light access mechanism 30. The light approach mechanism 30 allows at least one laser beam 40 to pass through the upper end member 20. In one example, at least one light access mechanism 30 is configured by one or more through holes. In another example, the light access mechanism 30 may include at least one window.

  The system 10 also includes a chuck 60. The chuck 60 has an upper surface 62, a lower surface 64, and an outer edge portion 66. The chuck 60 has a substantially cylindrical shape, is centered on the Z-center line CZ, has an upper surface 62 adjacent to the lower surface 24 of the upper end member 20 and parallel to the lower surface 24. The chuck 60 (and the accompanying center line CZ) is moved by the operation of the system 10 as will be described later. The upper surface 62 of the chuck 60 and the lower surface 24 of the top member 20 are separated by a distance D1 in the range of 50 microns to 1 mm, thereby defining a processing chamber interior (“inside”) 70 having a distance D1. In one example, the upper surface 52 of the semiconductor substrate (“wafer”) 50 and the lower surface 24 of the top member 20 define an interior 70 and a distance D1.

The upper surface 62 of the chuck 60 is configured to support the wafer 50. The wafer 50 has an upper surface 52, a lower surface 54, and an outer edge portion 56. In one example, the wafer 50 is a silicon wafer. Wafer 50 may be a product wafer. The product wafer is subjected to a process for manufacturing a semiconductor device, and further processed by the laser beam 40. The wafer 50 is indicated by a dashed circle in the top view of FIG. 2A. In one example, the chuck 60 is heated, in a further example, configured to heat the wafer 50 to the wafer temperature T _W of up to about 400 ° C.. In one example, at least one laser beam 40 is comprised of one or more annealing laser beams. That is, the at least one laser beam 40 is composed of one or more laser beams capable of performing an annealing process on the wafer 50 such as dopant diffusion.

  System 10 includes an insulating layer 80. The heat insulating layer 80 has an upper surface 82, a lower surface 84, and an outer edge portion 86. The heat insulating layer 80 is disposed in contact with the lower surface 64 of the chuck 60, so that the heat insulating layer 80 performs heat transfer with the chuck 60. In one example, the thermal insulation layer 80 is formed of a glass or ceramic material, or is a gap. In one example, the upper surface 82 of the heat insulating layer 80 is in intimate contact with the lower surface 64 of the chuck 60.

  The system 10 also includes a cooling device 90. The cooling device 90 is configured to manage heat generated due to the chuck 60 and a laser beam 40 incident on the wafer 50 as described below. The exemplary cooling device 90 has an upper surface 92, a lower surface 94, and an outer edge 96. The cooling device 90 optionally includes a recess 98. The recess 98 is defined by the support surface 100 and the inner wall 102. The recess 98 is configured to accommodate the heat insulating layer 80 and the chuck 60, whereby the heat insulating layer 80 is supported by the support surface 100.

  In one example, the inner wall 102 of the cooling device 90 and the outer edges 86 and 66 of the thermal insulation layer 80 and chuck 60 define a gap G1. In a further example, the cooling device 90 includes one or more gas flow paths 104. The gas flow path 104 provides a gas flow path from the support surface 100 to the lower surface 94. As a result, the gas 202 in the interior 70 that enters the gap G <b> 1 can flow out of the interior 70 at the lower surface 94 through the cooling device 90. The heat insulating layer 80 may be a void.

  System 10 also includes a movable stage 120. The movable stage 120 has an upper surface 122 and a lower surface 124. System 10 further includes an annular member 150. The annular member 150 is disposed adjacent to the outer edge 96 of the cooling device 90 and is attached to a water cooled reflective skirt (not shown) that surrounds the chuck assembly 68 and moves with the chuck assembly 68. The annular member 150 has a main body 151 and includes an upper surface 152, a lower surface 154, an inner surface 155, and an outer edge 156. The combination of the chuck 60, the heat insulating layer 80, and the cooling device 90 constitutes a chuck assembly 68. A combination of the chuck assembly 68, the movable stage 120, and the annular member 150 constitutes a movable stage assembly 128. The upper end member 20 is fixed with respect to the movable stage assembly 128. The movable stage assembly 128 has an outer periphery 129. In one example, the outer periphery 129 is defined in part by the outer edge 156 of the annular member 150.

  The movable stage 120 supports the cooling device 90 on the upper surface 122. The movable stage 120 is operably connected to the positioner 126. The positioner 126 is configured to move the movable stage 120 and position the movable stage 120 as necessary while tracking the position of the movable stage 120 with respect to the reference position. The movable stage 120 is operably supported on the platen 130 having the upper surface 132 in such a way that it can move in the XY plane.

  The lower surface 24 of the upper end member 20, the outer edge 156 of the annular member 150, and the upper surface 132 of the platen 130 define a gas curtain region 158.

  In one example, movable stage 120 and chuck 60 are integrated to form a single movable chuck or a two-part movable chuck that is operably connected to positioner 126. The upper end member 20 is sufficiently long in the X direction so that the chuck 60 can move relative to the upper end member 20, and the laser beam 40 can expose the entire upper surface 52 of the wafer 50.

The system 10 also includes at least one gas supply system 200 and at least one coolant supply system 250 that supplies the coolant 252. In one example, the first gas supply system 200 is configured to supply the gas 202 to the interior 70. On the other hand, another gas supply system 200 is configured to supply the gas 202 to the annular member 150. In one example embodiment, different gas supply systems 200 supply different gases 202. On the other hand, in another embodiment, different gas supply systems 200 supply the same gas 202. The annular member 150 is configured to control the flow of the gas 202 toward the peripheral gap G3 and forms a gas curtain (not shown). The peripheral gap G3 has a width or dimension _WG3 .

  In another embodiment, a single gas supply system 200 is employed to supply gas 202 to the interior 70 and the annular member 150. The example gas 202 may include one or more inert gases such as neon gas, argon gas, helium gas, and nitrogen gas. In one example, gas 202 comprises one or more inert gases. In other examples, the gas 202 includes a limited amount of one or more reactive gases such as oxygen gas. As will be described later, the gas 202 contains a forming gas or consists of a forming gas. The forming gas includes hydrogen gas and nitrogen gas.

The system 10 also includes a control unit 300. As described in US Pat. No. 9,029,809, the control unit 300 is operatively connected to the gas supply system 200 and the coolant supply system 250 and controls the operation of these systems 200 and 250. Thus, a gas curtain is formed. System 10 includes a vacuum system 260. The vacuum system 260 is pneumatically connected to the interior 70 via, for example, at least one gas flow path 104 including a gap G2 having a width W _G2 . The vacuum system 260 can be used to create a vacuum in the interior 70.
<Localized control of ambient oxygen during laser annealing>

  FIG. 2 is a simplified diagram of the system 10 of FIG. 1 and illustrates an example of the annealing process and ambient oxygen gas localization control process described herein. FIG. 3A is an enlarged view showing a part of the inner surface 70 and the upper surface 52 of the wafer 50 before annealing by the laser beam 40 and after introduction of the forming gas 202 into the inner surface 70. The forming gas 202 is shown mixed with the oxygen gas 205. FIG. 3B is an enlarged view of the laser beam 40 that anneals the upper surface 52 of the wafer 50 at the annealing position 55.

As described above, it is desirable to further reduce the concentration C _OX of the oxygen gas 205 in the interior 70 to further reduce the amount of oxidation that can occur on the upper surface 52 of the wafer 50. This phenomenon can be achieved anywhere in the interior 70, but in practice only the oxygen gas concentration needs to be reduced at the annealing location 55 where laser annealing is performed.

Thus, in one example of the method disclosed herein, the gas 202 is hydrogen gas and an inert buffer gas, such as 5 vol% hydrogen gas (H ₂ ) and 95 vol% nitrogen. A forming gas 202 made of a gas (N ₂ ) mixture is supplied to the interior 70. The interior 70 is degassed by operation of the vacuum system 260 (e.g., under vacuum), thereby containing oxygen gas 205 at an initial concentration or background concentration _COX . In one example, the initial or background concentration C _OX is as low as about 50 ppm. When the forming gas 202 is introduced into the interior 70, as shown in FIG. 3A, the forming gas 202 is immediately dispersed (diffused) to any location in the interior 70 including the region in contact with the upper surface 52 of the wafer 50, and oxygen gas 205 and Mix.

  The forming gas 202 can be injected into the interior 70 by the operation of the gas supply system 200 before or during the annealing process. Here, the laser beam 40 is configured to be incident on the upper surface 52 of the wafer 50, and the wafer 50 is moved with respect to the laser beam 40 by moving the chuck 60 as indicated by an arrow AR. 40 scans the upper surface 52 of the wafer 50. In one example, the partial pressure of forming gas 202 within interior 70 is in the range of about 1 millitorr to about 1000 torr. The range of partial pressure of forming gas 202 is preferably from about 1 millitorr to about 1000 millitorr. In one example, the pressure in the interior 70 is less than 760 Torr, ie less than 1 atmosphere.

During the annealing process of an example shown in FIG. 3B, the laser beam 40, in the annealing position 55, to heat the upper surface 52 of the wafer 50 to an annealing temperature T _A. The annealing temperature _{T A} is close to or wafer melting temperature _{T M,} or greater than wafer melting temperature _{T M.} The wafer melting temperature T _{M for} silicon is nominally T _M = 1,414 ° C. In the non-melt laser annealing, the annealing temperature _{T A} of the upper surface 52 of the wafer 50 is within 400 ° C. of the wafer melting temperature _{T M.} In the melt annealing, a _{T A} ≧ _{T M.} When the wafer 50 is scanned (ie moved relative to the laser beam 40), the annealing position 55 “moves” relative to the upper surface 52 of the wafer 50, but within the interior 70 relative to its initial position. Note that it is in a fixed state.

The heating of the upper surface 52 of the wafer 50 by the laser beam 40 at the annealing position 55 also acts to locally heat the forming gas 202 and the oxygen gas 205 in the interior 70, particularly around the annealing position 55. The forming gas temperature T _FG typically varies spatially within the interior 70 corresponding to the proximity of the forming gas 202 to the annealing position 55. That is, as the annealing position 55 is approached, the forming gas temperature _TFG increases. It is noted here that the amount of forming gas 202 is significantly greater than the amount of oxygen gas 205 (initial concentration C _OX ), so that the “gas” temperature in the interior 70 is basically It is defined by the forming gas 202.

2, 3A, and 3B, in conjunction with the local heating of the upper surface 52 of the wafer 50 in the annealing position 55, respectively the combustion temperature curve _{T C} for forming gas temperature _{T FG.} Combustion temperature curve T _C represents the combustion temperature in the following combustion reactions occur in any chamber pressure in the interior 70.
2H ₂ + O ₂ → 2H ₂ O vapor Formula 1
Combustion temperature curve _{T C} defines a local region RG. Local region RG includes a hemispherical portion nominally centered on annealing position 55 of interior 70. Within the local region RG, forming gas 202 has a _{T C} or more forming gas temperature _{T FG (T FG ≧ T C} ). Thus, the forming gas 202 represents the volume within the interior 70 where the combustion reaction of Equation 1 occurs.

The combustion reaction of Equation 1 acts to reduce the concentration of the oxygen gas 205 from the initial concentration or background concentration C _OX to a lower concentration (low value) C ′ _OX within the local region RG. Outside the local region RG in the interior 70, oxygen gas is present at an initial concentration or background concentration C _OX . This is schematically shown in FIG. 3B. In FIG. 3B, the concentration C _OX of the oxygen gas 205 outside the local region RG is higher than the concentration C ′ _OX in the local region RG (ie, C _OX > C ′ _OX ).

Thus, the forming gas 202 functions to locally control (reduce) the amount of the oxygen gas 205 in the local region RG. This control occurs via the combustion reaction of Equation 1. In this combustion reaction, oxygen molecules (O ₂ ) are cleaved into O atoms, and then the O atoms are combined with two hydrogen atoms (2H) derived from the forming gas 202 to form H ₂ O (water) vapor. Generating. This local processing occurs in the local region RG and reduces the amount of oxidation of the upper surface 52 of the wafer 50. Oxidation of the upper surface of the wafer 50 can occur during annealing. In one example, the concentration C ′ _OX of the oxygen gas 205 in the local region RG is C ′ _OX ≦ 10 ppm.

In one example embodiment, the combustion temperature within the range of partial pressures of interior 70 described above is T _C = about 600 ° C. Assuming a substantially hemispherical local region RG centered around the normal annealing position 55, the radius r _G of the local region RG at T _C = 600 ° C. may be r _G = about 1 micron to about 10 mm. The concentration of H atoms in the forming gas 202, the diffusion rate of H atoms in the interior 70, the initial concentration C _OX of the oxygen gas 205 in the interior 70, and the rate of the combustion reaction in Equation 1 are all the same as those in Equation 1. It is set so that the combustion reaction of Equation 1 can be sustained in such a way that the oxygen gas concentration C _OX in the local region RG can be substantially reduced compared to the starting or initial oxygen concentration C _OX. .

It will be apparent to those skilled in the art that various modifications can be made to the preferred embodiments of the disclosure described herein without departing from the spirit or scope of the disclosure as defined by the appended claims. Changes can be made. Accordingly, this disclosure includes modifications and variations of this disclosure that come within the scope of the appended claims and their equivalents.

  The present disclosure relates to laser annealing, and in particular, to a laser annealing method using localized oxygen gas localization control.

  The entire disclosure of any publication or patent document mentioned in this specification is hereby incorporated by reference. Publications or patent documents include US Pat. No. 5,997,963 (hereinafter referred to as the '963 patent), US Pat. No. 6,747,245; US Pat. No. 7,098,155; US Patent No. 7,157,660; US Patent No. 7,763,828; US Patent No. 8,309,474 and US Patent No. 9,029,809.

  Laser annealing (also called laser spike annealing, laser thermal annealing, laser heat treatment, etc.) is used for various applications in semiconductor manufacturing. Various applications also include activating dopants in selected regions of equipment (structures) formed on a semiconductor wafer when forming active microcircuits such as transistors and related types of semiconductor features.

  The laser annealing process is typically performed under vacuum in a processing chamber (or reaction chamber) such as, for example, a microchamber described in the '344 publication and the' 963 patent. One reason for using a vacuum is to reduce the amount of oxygen gas present on the surface of the semiconductor wafer being processed. This is because oxygen gas is highly reactive and oxidizes the semiconductor wafer surface. This is especially true in the case of laser annealing at high temperatures, since the oxidation rate increases with increasing temperature.

  Under normal vacuum conditions, the oxygen gas concentration inside the processing chamber can be reduced to about 50 parts per million (ppm) (vol.). Further reducing the oxygen gas concentration is problematic and requires not only substantial improvements in the processing chamber, but also expensive equipment (eg, more powerful vacuum pumps).

  Therefore, it is desirable to reduce the amount of oxygen gas on the surface of the semiconductor wafer to be laser annealed in a low cost and simple manner beyond what is possible with a conventional vacuum approach.

One aspect of the present disclosure is a method of laser annealing a semiconductor wafer having a surface. The method includes positioning a semiconductor wafer within the processing chamber, pulling the inside of the processing chamber to the vacuum, the process chamber interior, and be made to contain O ₂ by initial O ₂ concentration, H ₂ and buffer Introducing a forming gas containing a gas into the processing chamber; passing a laser beam into the processing chamber; and causing the laser beam to enter an annealing position on the surface of the semiconductor wafer. In the local region around the annealing position, where O ₂ and H ₂ are combusted to generate H ₂ O vapor, O ₂ and H ₂ of the forming gas are locally heated. This comprises reducing the O ₂ concentration in the local region compared to the initial O ₂ concentration.

Another aspect of the present disclosure is the above-described method, wherein the forming gas preferably includes 5 volume (vol)% H ₂ and 95 volume (vol)% N ₂ .

Another aspect of the present disclosure is in the aforementioned method, the local region, are preferably defined by a combustion temperature T _C in the range of 500 ° C. from 100 ° C..

  Another aspect of the present disclosure is the method described above, wherein the processing chamber is preferably a microchamber.

  Another aspect of the present disclosure is the above method, further comprising moving the semiconductor wafer relative to the laser beam, whereby the annealing position moves relative to a surface of the semiconductor wafer. Preferably, it is in a fixed position relative to its initial position inside the processing chamber.

Another aspect of the present disclosure is the above-described method, wherein the initial O ₂ concentration is preferably 50 ppm (vol.) Or more. The O ₂ concentration in the local region is preferably 10 ppm (vol.) Or less.

Another aspect of the present disclosure is in the aforementioned method, the semiconductor wafer preferably has a melting temperature T _M. Annealing of the surface of the semiconductor wafer is preferably carried out at an annealing temperature T _A. Here _is a _T A <T _M.

  Another aspect is a method for reducing oxygen gas in a local region around an annealing position during annealing of a semiconductor wafer having a surface. The method includes introducing a forming gas containing hydrogen gas and a buffer gas into the processing chamber containing the semiconductor wafer and the initial concentration of the oxygen gas, and laser annealing the surface of the semiconductor wafer, thereby In the local region around the annealing position, where the oxygen gas and the hydrogen gas burn and the water vapor is generated, the oxygen gas and the hydrogen gas of the forming gas are locally heated, thereby Reducing the oxygen gas concentration in the local region compared to the initial oxygen gas concentration.

Another aspect of the present disclosure is the above-described method, wherein the forming gas preferably includes 5% (vol)% hydrogen gas and 95% (vol)% nitrogen gas.

Another aspect of the present disclosure is in the aforementioned method, the local region, are preferably defined by a combustion temperature T _C in the range of 500 ° C. from 100 ° C..

  Another aspect of the present disclosure is the method described above, wherein the processing chamber is preferably a microchamber.

  Another aspect of the present disclosure is the method described above, wherein the processing chamber preferably has a pressure less than atmospheric pressure.

  Another aspect of the present disclosure is the above method, further comprising moving the semiconductor wafer relative to the laser beam, whereby the annealing position moves relative to a surface of the semiconductor wafer. Preferably, it is in a fixed position relative to its initial position inside the processing chamber.

Another aspect of the present disclosure is the method described above, wherein the initial concentration of the oxygen gas is preferably 50 ppm (vol.) Or more. The O ₂ concentration in the local region is preferably 10 ppm (vol.) Or less.

Another aspect of the present disclosure is in the aforementioned method, the semiconductor wafer preferably has a melting temperature T _M. Annealing of the surface of the semiconductor wafer is preferably carried out at an annealing temperature T _A. Here _is a _T A <T _M.

Another aspect of the present disclosure is a method of laser annealing a semiconductor wafer having a surface. In this method, a semiconductor wafer is disposed inside a processing chamber containing O ₂ at an initial O ₂ concentration, a forming gas containing H ₂ and a buffer gas is introduced into the processing chamber, and a laser is introduced into the processing chamber. A laser beam is incident on an annealing position on the surface of the semiconductor wafer, thereby annealing the surface of the semiconductor wafer, and a local region around the annealing position, wherein O ₂ and H ₂ In a local region where combustion occurs and generates H ₂ O vapor, O ₂ and the H ₂ of the forming gas are locally heated, thereby reducing the O ₂ concentration in the local region compared to the initial O ₂ concentration. Providing.

Another aspect of the present disclosure is the above-described method, preferably further including drawing a vacuum after the semiconductor wafer is disposed inside the processing chamber. The initial O ₂ concentration is defined by the amount of O ₂ remaining (concentration) remaining in the processing chamber after the vacuum is pulled.

Another aspect of the present disclosure is the above-described method, wherein the initial O ₂ concentration is preferably 50 ppm (vol.) Or more. The O ₂ concentration in the local region is preferably 10 ppm (vol.) Or less.

  Another aspect of the present disclosure is the method described above, wherein the processing chamber is preferably a microchamber.

Another aspect of the present disclosure is the above-described method, wherein the forming gas preferably includes 5% (vol)% hydrogen gas and 95% (vol)% nitrogen gas.

  Additional features and advantages are specified in the detailed description below. Some of them will be readily apparent to those skilled in the art from the description in the detailed description, or may be recognized by implementing the embodiments described in the detailed description, the claims, and the accompanying drawings. Let's go. It is to be understood that the foregoing summary and the following detailed description are exemplary only and provide a general outline or framework for understanding the nature and features of the present invention as set forth in the claims. Should be understood.

The accompanying drawings are included to provide a further understanding, and constitute a part of this specification and are incorporated into this specification. The drawings illustrate one or more embodiments, and together with the detailed description serve to explain the principles and operations of the various embodiments. Thus, the present disclosure will become more fully understood from the detailed description set forth below when taken in conjunction with the accompanying drawings.
FIG. 1A is an (XZ plane) of an example embodiment of a processing chamber system suitable for use in performing the annealing method and ambient oxygen gas (O ₂ ) localization control method disclosed herein. FIG. FIG. 1B is an exploded view of several major components of the processing chamber system of FIG. 1A. FIG. 1C is a top view (in the XY plane) showing the processing chamber system of FIG. 1A, along with line 1-1 showing the cross section of FIG. 1A. FIG. 2 is a simplified diagram of the processing chamber system of FIG. 1A illustrating an example annealing method that includes the formation of local regions using forming gas to perform localization control of ambient oxygen gas. is there. FIG. 3A is an enlarged view of the surface of the semiconductor wafer inside the processing chamber after introduction of the forming gas, and shows how the forming gas and oxygen gas are normally distributed uniformly on the surface of the semiconductor wafer prior to laser annealing. FIG. FIG. 3B is an enlarged view of a local region generated during the laser annealing process and surrounding the annealing position on the semiconductor wafer surface. In this laser annealing process, the oxygen gas concentration in the local region becomes lower than the oxygen gas concentration in other parts inside the processing chamber due to a decrease in the oxygen gas amount (concentration) in the local region.

  Hereinafter, various embodiments of the present disclosure and examples shown in the accompanying drawings will be described in detail. Wherever possible, the same or similar reference numbers and reference numerals are used in the drawings of the same or similar parts. The drawings are not to scale and those skilled in the art will recognize that the drawings have been simplified to illustrate the major portions of the present invention.

  The following claims are hereby incorporated into and constitute a part of the detailed description of the invention.

  The entire disclosure of any publication or patent document mentioned in this specification is incorporated by reference.

  In some of the drawings, Cartesian coordinates are drawn for reference, but this does not limit the orientation and location.

In the following description, the term “evacuating” or the term “vacuum” related to the inside of the processing chamber means reducing the pressure inside the processing chamber to below ambient pressure or atmospheric pressure outside the processing chamber. However, it does not necessarily mean that all atoms are removed (evacuated) from the inside of the processing chamber. Exemplary methods disclosed herein include evacuating the process chamber and / or evacuating the process chamber. In this method, the initial concentration C _{OX of} oxygen gas remains in the processing chamber. Here, the term “initial concentration” means that the method of performing localized control of the oxygen gas volume in the processing chamber starts with this concentration and ends with a reduced concentration compared to the initial concentration C _OX. Used to mean implemented.

  The terms “processing” and “method” are used interchangeably herein.

The expression “localized oxygen gas localization control” is understood to mean that the oxygen gas amount (concentration) decreases locally with respect to the initial amount (concentration) of oxygen gas.
<Processing chamber system>

FIG. 1A is a schematic cross-sectional view (in the XZ plane) of an example embodiment of a processing chamber system (“system”) 10 suitable for use in performing the methods disclosed herein. FIG. 1B is an exploded view of some major components of the system 10 of FIG. 1A. FIG. 1C is a top view (in the XY plane) showing the system 10 of FIG. 1A, along with line 1-1 showing the cross section of FIG. 1A. 1A to 1C represent a type of processing chamber derived from the '344 publication and called a “microchamber”.

  The system 10 has a Z-center line CZ extending in the Z direction and an X-center line CX extending in the X direction. The system 10 resides in an ambient environment 8 that can include at least one reactive gas such as, for example, oxygen gas. The ambient environment 8 may also include a non-reactive gas such as neon gas or argon gas, or a stable gas such as nitrogen gas.

  System 10 includes an upper end member 20. The upper end member 20 has an upper surface 22, a lower surface 24, and an outer edge portion 26. In one example, the upper end member 20 is substantially rectangular and has a parallel upper surface 22 and lower surface 24. In one example, the upper end member 20 is cooled, as will be described in more detail below. In one example, the upper end member 20 includes at least one light access mechanism 30. The light approach mechanism 30 allows at least one laser beam 40 to pass through the upper end member 20. In one example, at least one light access mechanism 30 is configured by one or more through holes. In another example, the light access mechanism 30 may include at least one window.

  The system 10 also includes a chuck 60. The chuck 60 has an upper surface 62, a lower surface 64, and an outer edge portion 66. The chuck 60 has a substantially cylindrical shape, is centered on the Z-center line CZ, has an upper surface 62 adjacent to the lower surface 24 of the upper end member 20 and parallel to the lower surface 24. The chuck 60 (and the accompanying center line CZ) is moved by the operation of the system 10 as will be described later. The upper surface 62 of the chuck 60 and the lower surface 24 of the top member 20 are separated by a distance D1 in the range of 50 microns to 1 mm, thereby defining a processing chamber interior (“inside”) 70 having a distance D1. In one example, the upper surface 52 of the semiconductor substrate (“wafer”) 50 and the lower surface 24 of the top member 20 define an interior 70 and a distance D1.

The upper surface 62 of the chuck 60 is configured to support the wafer 50. The wafer 50 has an upper surface 52, a lower surface 54, and an outer edge portion 56. In one example, the wafer 50 is a silicon wafer. Wafer 50 may be a product wafer. The product wafer is subjected to a process for manufacturing a semiconductor device, and further processed by the laser beam 40. The wafer 50 is indicated by a dashed circle in the top view of FIG. 1C . In one example, the chuck 60 is heated, in a further example, configured to heat the wafer 50 to the wafer temperature T _W of up to about 400 ° C.. In one example, at least one laser beam 40 is comprised of one or more annealing laser beams. That is, the at least one laser beam 40 is composed of one or more laser beams capable of performing an annealing process on the wafer 50 such as dopant diffusion.

  System 10 includes an insulating layer 80. The heat insulating layer 80 has an upper surface 82, a lower surface 84, and an outer edge portion 86. The heat insulating layer 80 is disposed in contact with the lower surface 64 of the chuck 60, so that the heat insulating layer 80 performs heat transfer with the chuck 60. In one example, the thermal insulation layer 80 is formed of a glass or ceramic material, or is a gap. In one example, the upper surface 82 of the heat insulating layer 80 is in intimate contact with the lower surface 64 of the chuck 60.

  The system 10 also includes a cooling device 90. The cooling device 90 is configured to manage heat generated due to the chuck 60 and a laser beam 40 incident on the wafer 50 as described below. The exemplary cooling device 90 has an upper surface 92, a lower surface 94, and an outer edge 96. The cooling device 90 optionally includes a recess 98. The recess 98 is defined by the support surface 100 and the inner wall 102. The recess 98 is configured to accommodate the heat insulating layer 80 and the chuck 60, whereby the heat insulating layer 80 is supported by the support surface 100.

  In one example, the inner wall 102 of the cooling device 90 and the outer edges 86 and 66 of the thermal insulation layer 80 and chuck 60 define a gap G1. In a further example, the cooling device 90 includes one or more gas flow paths 104. The gas flow path 104 provides a gas flow path from the support surface 100 to the lower surface 94. As a result, the gas 202 in the interior 70 that enters the gap G <b> 1 can flow out of the interior 70 at the lower surface 94 through the cooling device 90. The heat insulating layer 80 may be a void.

  System 10 also includes a movable stage 120. The movable stage 120 has an upper surface 122 and a lower surface 124. System 10 further includes an annular member 150. The annular member 150 is disposed adjacent to the outer edge 96 of the cooling device 90 and is attached to a water cooled reflective skirt (not shown) that surrounds the chuck assembly 68 and moves with the chuck assembly 68. The annular member 150 has a main body 151 and includes an upper surface 152, a lower surface 154, an inner surface 155, and an outer edge 156. The combination of the chuck 60, the heat insulating layer 80, and the cooling device 90 constitutes a chuck assembly 68. A combination of the chuck assembly 68, the movable stage 120, and the annular member 150 constitutes a movable stage assembly 128. The upper end member 20 is fixed with respect to the movable stage assembly 128. The movable stage assembly 128 has an outer periphery 129. In one example, the outer periphery 129 is defined in part by the outer edge 156 of the annular member 150.

  The movable stage 120 supports the cooling device 90 on the upper surface 122. The movable stage 120 is operably connected to the positioner 126. The positioner 126 is configured to move the movable stage 120 and position the movable stage 120 as necessary while tracking the position of the movable stage 120 with respect to the reference position. The movable stage 120 is operably supported on the platen 130 having the upper surface 132 in such a way that it can move in the XY plane.

  The lower surface 24 of the upper end member 20, the outer edge 156 of the annular member 150, and the upper surface 132 of the platen 130 define a gas curtain region 158.

  In one example, movable stage 120 and chuck 60 are integrated to form a single movable chuck or a two-part movable chuck that is operably connected to positioner 126. The upper end member 20 is sufficiently long in the X direction so that the chuck 60 can move relative to the upper end member 20, and the laser beam 40 can expose the entire upper surface 52 of the wafer 50.

The system 10 also includes at least one gas supply system 200 and at least one coolant supply system 250 that supplies the coolant 252. In one example, the first gas supply system 200 is configured to supply the gas 202 to the interior 70. On the other hand, another gas supply system 200 is configured to supply the gas 202 to the annular member 150. In one example embodiment, different gas supply systems 200 supply different gases 202. On the other hand, in another embodiment, different gas supply systems 200 supply the same gas 202. The annular member 150 is configured to control the flow of the gas 202 toward the peripheral gap G3 and forms a gas curtain (not shown). The peripheral gap G3 has a width or dimension _WG3 .

  In another embodiment, a single gas supply system 200 is employed to supply gas 202 to the interior 70 and the annular member 150. The example gas 202 may include one or more inert gases such as neon gas, argon gas, helium gas, and nitrogen gas. In one example, gas 202 comprises one or more inert gases. In other examples, the gas 202 includes a limited amount of one or more reactive gases such as oxygen gas. As will be described later, the gas 202 contains a forming gas or consists of a forming gas. The forming gas includes hydrogen gas and nitrogen gas.

The system 10 also includes a control unit 300. As described in US Pat. No. 9,029,809, the control unit 300 is operatively connected to the gas supply system 200 and the coolant supply system 250 and controls the operation of these systems 200 and 250. Thus, a gas curtain is formed. System 10 includes a vacuum system 260. The vacuum system 260 is pneumatically connected to the interior 70 via, for example, at least one gas flow path 104 including a gap G2 having a width W _G2 . The vacuum system 260 can be used to create a vacuum in the interior 70.
<Localized control of ambient oxygen during laser annealing>

FIG. 2 is a simplified diagram of the system 10 of FIG. 1A and illustrates an example of the annealing process and the ambient oxygen gas localization control process described herein. FIG. 3A is an enlarged view showing a part of the inner surface 70 and the upper surface 52 of the wafer 50 before annealing by the laser beam 40 and after introduction of the forming gas 202 into the inner surface 70. The forming gas 202 is shown mixed with the oxygen gas 205. FIG. 3B is an enlarged view of the laser beam 40 that anneals the upper surface 52 of the wafer 50 at the annealing position 55.

As described above, it is desirable to further reduce the concentration C _OX of the oxygen gas 205 in the interior 70 to further reduce the amount of oxidation that can occur on the upper surface 52 of the wafer 50. This phenomenon can be achieved anywhere in the interior 70, but in practice only the oxygen gas concentration needs to be reduced at the annealing location 55 where laser annealing is performed.

Thus, in one example of the method disclosed herein, the gas 202 is hydrogen gas and an inert buffer gas, such as 5 vol% hydrogen gas (H ₂ ) and 95 vol% nitrogen. A forming gas 202 made of a gas (N ₂ ) mixture is supplied to the interior 70. The interior 70 is degassed by operation of the vacuum system 260 (e.g., under vacuum), thereby containing oxygen gas 205 at an initial concentration or background concentration _COX . In one example, the initial or background concentration C _OX is as low as about 50 ppm. When the forming gas 202 is introduced into the interior 70, as shown in FIG. 3A, the forming gas 202 is immediately dispersed (diffused) to any location in the interior 70 including the region in contact with the upper surface 52 of the wafer 50, and oxygen gas 205 and Mix.

  The forming gas 202 can be injected into the interior 70 by the operation of the gas supply system 200 before or during the annealing process. Here, the laser beam 40 is configured to be incident on the upper surface 52 of the wafer 50, and the wafer 50 is moved with respect to the laser beam 40 by moving the chuck 60 as indicated by an arrow AR. 40 scans the upper surface 52 of the wafer 50. In one example, the partial pressure of forming gas 202 within interior 70 is in the range of about 1 millitorr to about 1000 torr. The range of partial pressure of forming gas 202 is preferably from about 1 millitorr to about 1000 millitorr. In one example, the pressure in the interior 70 is less than 760 Torr, ie less than 1 atmosphere.

During the annealing process of an example shown in FIG. 3B, the laser beam 40, in the annealing position 55, to heat the upper surface 52 of the wafer 50 to an annealing temperature T _A. The annealing temperature _{T A} is close to or wafer melting temperature _{T M,} or greater than wafer melting temperature _{T M.} The wafer melting temperature T _{M for} silicon is nominally T _M = 1,414 ° C. In the non-melt laser annealing, the annealing temperature _{T A} of the upper surface 52 of the wafer 50 is within 400 ° C. of the wafer melting temperature _{T M.} In the melt annealing, a _{T A} ≧ _{T M.} When the wafer 50 is scanned (ie moved relative to the laser beam 40), the annealing position 55 “moves” relative to the upper surface 52 of the wafer 50, but within the interior 70 relative to its initial position. Note that it is in a fixed state.

The heating of the upper surface 52 of the wafer 50 by the laser beam 40 at the annealing position 55 also acts to locally heat the forming gas 202 and the oxygen gas 205 in the interior 70, particularly around the annealing position 55. The forming gas temperature T _FG typically varies spatially within the interior 70 corresponding to the proximity of the forming gas 202 to the annealing position 55. That is, as the annealing position 55 is approached, the forming gas temperature _TFG increases. It is noted here that the amount of forming gas 202 is significantly greater than the amount of oxygen gas 205 (initial concentration C _OX ), so that the “gas” temperature in the interior 70 is basically It is defined by the forming gas 202.

2, 3A, and 3B, in conjunction with the local heating of the upper surface 52 of the wafer 50 in the annealing position 55, respectively the combustion temperature curve _{T C} for forming gas temperature _{T FG.} Combustion temperature curve T _C represents the combustion temperature in the following combustion reactions occur in any chamber pressure in the interior 70.
2H ₂ + O ₂ → 2H ₂ O vapor Formula 1
Combustion temperature curve _{T C} defines a local region RG. Local region RG includes a hemispherical portion nominally centered on annealing position 55 of interior 70. Within the local region RG, forming gas 202 has a _{T C} or more forming gas temperature _{T FG (T FG ≧ T C} ). Thus, the forming gas 202 represents the volume within the interior 70 where the combustion reaction of Equation 1 occurs.

The combustion reaction of Equation 1 acts to reduce the concentration of the oxygen gas 205 from the initial concentration or background concentration C _OX to a lower concentration (low value) C ′ _OX within the local region RG. Outside the local region RG in the interior 70, oxygen gas is present at an initial concentration or background concentration C _OX . This is schematically shown in FIG. 3B. In FIG. 3B, the concentration C _OX of the oxygen gas 205 outside the local region RG is higher than the concentration C ′ _OX in the local region RG (ie, C _OX > C ′ _OX ).

Thus, the forming gas 202 functions to locally control (reduce) the amount of the oxygen gas 205 in the local region RG. This control occurs via the combustion reaction of Equation 1. In this combustion reaction, oxygen molecules (O ₂ ) are cleaved into O atoms, and then the O atoms are combined with two hydrogen atoms (2H) derived from the forming gas 202 to form H ₂ O (water) vapor. Generating. This local processing occurs in the local region RG and reduces the amount of oxidation of the upper surface 52 of the wafer 50. Oxidation of the upper surface of the wafer 50 can occur during annealing. In one example, the concentration C ′ _OX of the oxygen gas 205 in the local region RG is C ′ _OX ≦ 10 ppm.

In one example embodiment, the combustion temperature within the range of partial pressures of interior 70 described above is T _C = about 600 ° C. Assuming a substantially hemispherical local region RG centered around the normal annealing position 55, the radius r _G of the local region RG at T _C = 600 ° C. may be r _G = about 1 micron to about 10 mm. The concentration of H atoms in the forming gas 202, the diffusion rate of H atoms in the interior 70, the initial concentration C _OX of the oxygen gas 205 in the interior 70, and the rate of the combustion reaction of Equation 1 are all the same as the combustion reaction of Equation 1. It is set so that the combustion reaction of Equation 1 can be sustained in such a way that it can be started and the oxygen gas concentration C ′ _OX in the local region RG is substantially reduced compared to the starting or initial oxygen concentration C _OX. The

  It will be apparent to those skilled in the art that various modifications can be made to the preferred embodiments of the disclosure described herein without departing from the spirit or scope of the disclosure as defined by the appended claims. Changes can be made. Accordingly, this disclosure includes modifications and variations of this disclosure that come within the scope of the appended claims and their equivalents.

Claims (20)

A method of laser annealing a semiconductor wafer having a surface,
Placing a semiconductor wafer inside the processing chamber;
Evacuating the interior of the process chamber such that the interior of the process chamber contains O ₂ at an initial O ₂ concentration;
Introducing a forming gas comprising H ₂ and a buffer gas into the processing chamber;
A laser beam is passed through the processing chamber, and the laser beam is incident on an annealing position of the semiconductor wafer surface;
Thereby, the surface of the semiconductor wafer is annealed, and in the local region around the annealing position where O ₂ and H ₂ are burned to generate H ₂ O vapor, O ₂ and the forming are performed. Heating the gas H ₂ locally, thereby reducing the O ₂ concentration in the local region compared to the initial O ₂ concentration. The method of claim 1, wherein the forming gas comprises 5 volume (vol)% H ₂ and 95 volume (vol)% N ₂ . The method according to claim 1 or 2, wherein the local region is defined by a combustion temperature T _C in the range of 100 ° C to 500 ° C.   4. A method according to any one of claims 1 to 3, wherein the processing chamber comprises a microchamber.   Moving the semiconductor wafer relative to the laser beam so that the annealing position moves relative to the surface of the semiconductor wafer but is fixed relative to its initial position within the processing chamber. The method according to any one of claims 1 to 4, wherein the method is in a position. The method according to any one of claims 1 to 5, wherein the initial O ₂ concentration is 50 ppm (vol.) Or more, and the decreased O ₂ concentration is 10 ppm (vol.) Or less. 7. The semiconductor wafer according to claim 1, wherein the semiconductor wafer has a melting temperature T _M , and the annealing of the surface of the semiconductor wafer is performed at the annealing temperature T _A , where T _A <T _M. The method according to item. A method for reducing oxygen gas in a local region around an annealing position during annealing of a semiconductor wafer having a surface comprising:
Introducing a forming gas containing a hydrogen gas and a buffer gas into the processing chamber containing the semiconductor wafer and the oxygen gas having an initial concentration;
Laser annealing the surface of the semiconductor wafer,
Accordingly, the oxygen gas and the hydrogen gas of the forming gas are locally heated in a local region around the annealing position, where the oxygen gas and the hydrogen gas are burned to generate water vapor. And thereby reducing the oxygen gas concentration in the local region compared to the initial oxygen gas concentration.   9. The method of claim 8, wherein the buffer gas comprises 5 volume (vol)% hydrogen gas and 95 volume (vol) nitrogen gas. The local region is defined by the combustion temperature T _C in the range of 500 ° C. from 100 ° C., The method according to claim 8 or 9.   11. A method according to any one of claims 8 to 10, wherein the processing chamber comprises a microchamber.   12. A method according to any one of claims 8 to 11 wherein the processing chamber has a pressure less than atmospheric pressure.   Further comprising moving the semiconductor wafer relative to the laser beam so that the annealing position moves relative to the surface of the semiconductor wafer but is fixed relative to its initial position within the processing chamber. 13. A method according to any one of claims 8 to 12 in a defined position.   14. The method according to claim 8, wherein an initial concentration of the oxygen gas is 50 ppm (vol.) Or more and a reduced oxygen concentration is 10 ppm (vol.) Or less. 15. The semiconductor wafer according to claim 8, wherein the semiconductor wafer has a melting temperature T _M , and the annealing of the surface of the semiconductor wafer is performed at the annealing temperature T _A , where T _A <T _M. The method according to item. A method of laser annealing a semiconductor wafer having a surface,
Placing a semiconductor wafer inside a processing chamber containing O ₂ at an initial O ₂ concentration;
Introducing a forming gas comprising H ₂ and a buffer gas into the processing chamber;
A laser beam is passed through the processing chamber, and the laser beam is incident on an annealing position of the semiconductor wafer surface;
Thereby, the surface of the semiconductor wafer is annealed, and in the local region around the annealing position where O ₂ and H ₂ are burned to generate H ₂ O vapor, O ₂ and the forming are performed. Heating the gas H ₂ locally, thereby reducing the O ₂ concentration in the local region compared to the initial O ₂ concentration. The method further comprises drawing a vacuum after placing the semiconductor wafer inside the processing chamber, wherein the initial O ₂ concentration is defined by the amount of residual O ₂ remaining in the processing chamber after drawing the vacuum. Item 17. The method according to Item 16. The initial _{O 2} concentration, the initial _{O 2} concentration is at 50 ppm (vol.) Or higher, reduced the _{O 2} concentration is 10 ppm (vol.) Or less The method of claim 17.   The method according to any one of claims 16 to 18, wherein the processing chamber comprises a microchamber. 20. The method according to any one of claims 16 to 19, wherein the buffer gas comprises 5 volume (vol)% hydrogen gas and 95 volume (vol) nitrogen gas.

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