JP2014138173A - Method of manufacturing semiconductor device, and substrate processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time to use an accelerator for forming an n-layer.SOLUTION: A method of manufacturing a semiconductor device comprises: an irradiation step (S10) of irradiating a substrate with a particle beam by an accelerator; and an annealing step (S12) of heat-treating the substrate in an atmosphere containing hydrogen in order to form an n-layer in the substrate. In the irradiation step (S10), the substrate is irradiated with the particle beam containing hydrogen ions so as not to reach the hydrogen quantity required for forming the n-layer, or the substrate is irradiated with the particle beam containing no hydrogen ion.

Description

  The present invention relates to a semiconductor device manufacturing method and a substrate processing system.

  2. Description of the Related Art There is known a method for manufacturing a silicon semiconductor device including ion implantation of protons (hydrogen ions) into a silicon substrate and heat treatment to reduce resistivity and form a channel stop layer.

Japanese Patent Laid-Open No. 9-260639 JP 2008-10846 A

  In recent years, in certain types of semiconductor devices, it may be desired to provide a thick n layer with a high concentration. IGBT is a typical example. The process of forming the n layer may include a step of injecting hydrogen into the substrate using an accelerator. The higher the concentration and thickness of the target n-layer, the greater the amount of hydrogen injected and the longer the time for using the accelerator. The accelerator is relatively expensive to operate. Therefore, the longer the accelerator usage time, the higher the manufacturing cost of the resulting device.

  One exemplary object of an aspect of the present invention is to provide a method of manufacturing a semiconductor device and a substrate processing system that can shorten the use time of an accelerator for forming an n layer.

  According to an aspect of the present invention, an irradiation step of irradiating the substrate with a particle beam using an accelerator, and an annealing step of heat-treating the substrate in an atmosphere containing hydrogen to form an n layer on the substrate, A method for manufacturing a semiconductor device is provided. In the irradiation step, the substrate is irradiated with a particle beam containing hydrogen ions so as not to reach a required hydrogen amount for forming the n layer, or a particle beam not containing hydrogen ions is irradiated onto the substrate. Prepare for that.

  The particle beam not containing hydrogen ions may contain light ions excluding hydrogen ions. The particle beam may be a helium ion beam.

  The accelerator may be a circular accelerator, a linear accelerator, or an electrostatic accelerator. The accelerator may be a cyclotron.

  According to an aspect of the present invention, a particle beam irradiation apparatus including an accelerator for irradiating a substrate with a particle beam, and an annealing apparatus that heat-treats the substrate in an atmosphere containing hydrogen to form an n layer on the substrate. A substrate processing system is provided. The particle beam irradiation apparatus irradiates the substrate with a particle beam containing hydrogen ions so as not to reach a required hydrogen amount for forming the n layer, or irradiates the substrate with a particle beam not containing hydrogen ions. To do.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, it is possible to shorten the use time of the accelerator for forming the n layer.

It is a figure which shows typically schematic structure of the manufacturing system which concerns on one embodiment of this invention. It is a figure which shows typically schematic structure of the particle beam irradiation apparatus which concerns on one embodiment of this invention. It is a flowchart for demonstrating the manufacturing method of the semiconductor device which concerns on one embodiment of this invention.

  FIG. 1 is a diagram schematically showing a schematic configuration of a manufacturing system 1 according to an embodiment of the present invention. The manufacturing system 1 is a substrate processing system used for introducing hydrogen into a semiconductor substrate (hereinafter also simply referred to as a substrate). The manufacturing system 1 includes a particle beam irradiation device 2 and an annealing device 3. The manufacturing system 1 first processes a substrate with the particle beam irradiation device 2, and then processes the substrate with the annealing device 3.

  A semiconductor substrate processed in the manufacturing system 1 is a substrate (for example, a wafer) on which a so-called vertical semiconductor device is finally formed. A vertical device is generally a device having a current path in a vertical direction between one surface (hereinafter also referred to as a front surface) and the other surface (hereinafter also referred to as a back surface) of a substrate. Used in power control applications. Such vertical devices include, for example, IGBTs and power control diodes. The hydrogen introduction method according to the present embodiment can be applied to any semiconductor substrate, and is not limited to use in the manufacturing process of the specific device described above.

  Prior to the hydrogen introduction process in the manufacturing system 1, an element structure including wiring is usually already formed on the front surface of the semiconductor substrate. By processing the substrate in the manufacturing system 1, as will be described in detail later, an n layer is formed in a certain depth range on the back side of the substrate.

  FIG. 2 is a diagram schematically showing a schematic configuration of the particle beam irradiation apparatus 2 according to an embodiment of the present invention. The particle beam irradiation apparatus 2 is configured to irradiate the substrate W with the particle beam B using the accelerator 10. The particle beam irradiation apparatus 2 includes an accelerator 10 as a particle beam source, a substrate transfer apparatus 12 that holds and transfers the substrate W for irradiation of the particle beam B, and a particle transfer B emitted from the accelerator 10 as a substrate transfer apparatus. A beam transport duct 14 leading to 12. As will be described later, the particle beam B contains helium ions.

  The accelerator 10 accelerates charged particles and emits charged particle beams. In the present embodiment, the accelerator 10 is a cyclotron. The substrate transport apparatus 12 includes an irradiation chamber 18 for irradiating the substrate W mounted on the transport plate 16 with the particle beam B, and a moving mechanism 20 that moves the transport plate 16 in the irradiation chamber 18. The transport plate 16 mounts a plurality of substrates W. The moving mechanism 20 moves the transport plate 16 so that all the substrates W mounted on one transport plate 16 are sequentially irradiated with the particle beam B. The moving mechanism 20 carries out the irradiation-treated transport plate 16 from the irradiation chamber 18 and loads the next transport plate 16 into the irradiation chamber 18. Further, in the middle of the beam transport duct 14, a vacuum pump for maintaining the inside in a vacuum, an electromagnetic coil for correcting the beam direction, and the like are provided.

  As described above, the manufacturing system 1 includes the annealing device 3. The annealing apparatus 3 heat-treats the substrate W that has been irradiated by the particle beam irradiation apparatus 2. The annealing apparatus 3 is configured to heat the substrate W in an atmosphere containing hydrogen. As will be described later, the annealing apparatus 3 introduces hydrogen into the substrate W by annealing in a hydrogen gas-containing atmosphere and electrically activates the hydrogen introduction layer of the substrate W. In this way, an n layer can be formed on the substrate W. As the annealing apparatus 3, any known appropriate annealing apparatus can be used.

  By the way, a typical method for forming an n layer on a semiconductor substrate using hydrogen includes hydrogen ion implantation into the substrate and subsequent annealing treatment. In this case, generally, the processing time of hydrogen ion implantation is set so as to reach a predetermined carrier (for example, electron) concentration by annealing. The carrier concentration tends to increase as the processing time is increased. Therefore, a long processing time is required to form a thick n-layer with a high concentration. Further, the annealing treatment is usually performed in an inert gas atmosphere such as nitrogen.

  One of the hydrogen ion sources is a cyclotron as described above. However, cyclotrons are relatively expensive to operate. Therefore, especially when forming a thick n-layer with a high concentration, the operating cost of the cyclotron greatly affects the manufacturing cost of the device. Therefore, it is desirable to shorten the operation time of the cyclotron or not to use the cyclotron in the manufacturing process for forming the n layer.

  In order to form an n-layer on a semiconductor substrate using hydrogen, it is considered necessary to have both hydrogen and lattice defects in a target depth range. According to the knowledge of the present inventors, when a substrate is irradiated with a hydrogen ion beam using a cyclotron, hydrogen and lattice defects are introduced into a target depth range. A plurality of lattice defects are formed per hydrogen ion. Therefore, the time required to reach a certain reference amount is shorter for lattice defects than for hydrogen. Therefore, in the existing hydrogen ion implantation, it is considered that a necessary number of lattice defects are formed in the substrate before hydrogen is introduced into the substrate in an amount necessary for forming the n layer.

  Therefore, in this embodiment, the hydrogen introduction process and the defect formation process are separated. That is, in this embodiment, a cyclotron is used to form lattice defects, and then hydrogen is introduced into the substrate without using the cyclotron. In this way, the use time of the cyclotron can be shortened.

  FIG. 3 is a flowchart for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention. This method is a method for forming an n layer on the substrate W. As shown in FIG. 3, this method includes an irradiation step (S10) and an annealing step (S12).

  In the irradiation step (S10), the particle beam irradiation apparatus 2 (see FIGS. 1 and 2) is used. The particle beam irradiation apparatus 2 irradiates the substrate W with the particle beam B using the accelerator 10, and forms lattice defects inside the substrate W. In the present embodiment, the particle beam B is a helium ion beam. Accordingly, the accelerator 10 accelerates helium ions and irradiates the substrate W with a helium ion beam. At this time, the substrate W is held so that the back surface of the substrate W is irradiated with the helium ion beam.

  Since the particle beam B is a helium ion beam, it does not contain hydrogen ions. Therefore, hydrogen is not injected into the substrate W in the irradiation step (S10).

  When the substrate W is irradiated with a helium ion beam using an accelerator such as a cyclotron, lattice defects are formed in a target depth range. Since helium ions are heavier than hydrogen ions, the defect generation rate per ion is increased, and the time required for defect formation processing can be shortened. Therefore, in order to shorten the time required for the defect formation process, it is desirable that the particle beam B does not contain hydrogen ions.

In the annealing step (S12), the annealing apparatus 3 (see FIG. 1) is used. The substrate W processed by the particle beam B is transferred from the particle beam irradiation apparatus 2 to the annealing apparatus 3 by an operator or by an appropriate transfer means. In the annealing apparatus 3, the back surface of the substrate W is exposed to an atmosphere containing hydrogen gas. The annealing device 3 heats the substrate W in an atmosphere containing hydrogen gas. Hydrogen enters lattice defects of the silicon substrate by the heat treatment. Hydrogen is introduced into the defect formation layer of the substrate W so as to satisfy the necessary amount of hydrogen for forming the n layer, and the hydrogen introduction layer thus obtained is activated. In this way, a relatively thick n layer can be formed on the back side of the substrate W. For example, the n layer is formed in the depth range of the maximum depth of 1 μm to 50 μm from the back surface of the substrate W. This n layer is suitable for an n ⁺ layer of IGBT, for example.

  In the annealing step (S12), it is preferable to set the pressure of the hydrogen gas-containing atmosphere to a relatively high pressure (for example, atmospheric pressure or higher pressure), since the entry of hydrogen into the substrate W is promoted. The substrate W is heated to a temperature selected from the range of 150 ° C. to 600 ° C. (preferably 300 ° C. to 500 ° C., more preferably 350 ° C. to 450 ° C.). The lower limit of this temperature range is determined to bring about the activation of the hydrogen introduction layer. The upper limit of the temperature range is determined so as to prevent damage to the element structure already formed on the front surface of the substrate W (for example, lower than the melting point of a metal (for example, aluminum) used for wiring).

  According to this embodiment, the operating time of the cyclotron can be halved, for example. As an example, when the operation time of the cyclotron is about 4 minutes in the above-described typical hydrogen ion implantation, the time required for the irradiation step (S10) of this method required to form the same n layer is about It is estimated that 2 minutes is sufficient. Thus, according to the present embodiment, the operating cost of the cyclotron in forming a thick n-layer with high concentration can be halved. Since the annealing step (S12) is also performed by an existing method, the cost effect is negligible. Further, since the irradiation process is a single wafer process, the annealing process is a batch process, and therefore hydrogen introduction by annealing is low cost. Therefore, according to the present embodiment, the n-layer forming process of the substrate can be performed at a lower cost than the existing method.

  In the above, this invention was demonstrated based on the Example. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, various modifications are possible, and such modifications are within the scope of the present invention. By the way.

  In the above-described embodiment, the process of newly forming the n layer on the substrate has been described. However, the method according to this embodiment can also be applied to a substrate on which the n layer has already been formed. In this way, it is possible to increase the carrier concentration of the substrate on which the n layer has already been formed. Therefore, a method for manufacturing a semiconductor device according to an embodiment includes an irradiation step of irradiating a particle beam using an accelerator on a substrate on which an n layer has already been formed, and an annealing for heat-treating the substrate in an atmosphere containing hydrogen. And a process.

  The particle beam B is not limited to a helium ion beam. For example, the particle beam B may be a light ion beam including light ions that are lighter than neon. However, the particle beam B does not contain hydrogen ions. Since these ions are heavier than hydrogen ions, the defect generation rate per ion increases, and the time required for defect formation processing can be shortened.

  In some embodiments, the particle beam B may include electrons. In the irradiation step (S 10), the substrate W may be irradiated with an electron beam using the accelerator 10 in order to form lattice defects inside the substrate W. In this case, the accelerator 10 can also be called an electron beam irradiation apparatus. Since the electron beam can be irradiated without opening the package (such as film or plastic) of the substrate W, the handling of the substrate W is easy and convenient.

  In some embodiments, the particle beam B may include neutrons. In the irradiation step (S10), in order to form lattice defects inside the substrate W, the substrate W may be irradiated with a neutron beam using the accelerator 10. In this case, the particle beam irradiation apparatus 2 may include a target that receives the charged particle beam emitted from the accelerator 10 and generates a neutron beam upstream of the beam transport duct 14.

  In the above-described embodiment, the defect formation process and the hydrogen introduction process are completely separated by using helium ions, but during the defect formation process of the substrate W by using the particle beam B containing hydrogen ions. It is also possible to implant some hydrogen ions. The amount of hydrogen injected in the irradiation step may be less than the required amount of hydrogen for forming the n layer. This is because the annealing treatment can supplement hydrogen. Even in this case, the irradiation time of the particle beam B can be shortened as compared with the existing method.

  The accelerator 10 is not limited to a cyclotron. By not using a cyclotron with a relatively high operating cost, the cost of forming the n layer on the substrate can be further reduced. The accelerator 10 may be a circular accelerator other than a cyclotron (for example, a synchrotron). Alternatively, the accelerator 10 may be a linear accelerator such as a linac that accelerates accelerated particles on a straight line, or may be an electrostatic accelerator such as a bandegraph or a tandem. Therefore, the particle beam irradiation apparatus 2 may be a high energy ion implantation apparatus.

  DESCRIPTION OF SYMBOLS 1 Manufacturing system, 2 Particle beam irradiation apparatus, 3 Annealing apparatus, 10 Accelerator, B particle beam, W board | substrate.

Claims (6)

An irradiation process of irradiating the substrate with particle beams using an accelerator;
An annealing step of heat-treating the substrate in an atmosphere containing hydrogen to form an n-layer on the substrate,
In the irradiation step, the substrate is irradiated with a particle beam containing hydrogen ions so as not to reach a required hydrogen amount for forming the n layer, or a particle beam not containing hydrogen ions is irradiated onto the substrate. The manufacturing method of the semiconductor device characterized by the above-mentioned.   The method according to claim 1, wherein the particle beam not containing hydrogen ions contains light ions excluding hydrogen ions.   The method according to claim 1, wherein the particle beam is a helium ion beam.   The method according to claim 1, wherein the accelerator is a circular accelerator, a linear accelerator, or an electrostatic accelerator.   The method according to claim 1, wherein the accelerator is a cyclotron. A particle beam irradiation apparatus including an accelerator for irradiating a particle beam to a substrate;
An annealing apparatus for performing a heat treatment of the substrate in an atmosphere containing hydrogen to form an n layer on the substrate,
The particle beam irradiation apparatus irradiates the substrate with a particle beam containing hydrogen ions so as not to reach a required hydrogen amount for forming the n layer, or irradiates the substrate with a particle beam not containing hydrogen ions. A substrate processing system.

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