JP4964736B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus.

  In recent years, miniaturization of circuit elements has become an important issue due to the demand for higher integration and higher density of integrated circuits (ICs). In particular, in a MOS (Metal-Oxide Semiconductor) transistor, if miniaturization of about 0.1 μm or more is promoted, the short channel effect becomes remarkable, and problems such as a decrease in threshold voltage and deterioration in off characteristics occur. In order to prevent the short channel effect of the MOS, it is effective to form a shallow impurity diffusion layer constituting each of the source and drain regions.

  The formation of the impurity diffusion layer is usually performed by implanting ionized impurities into the surface region of the substrate, heating the surface region of the substrate into which the impurities are implanted, and recovering lattice defects generated by the ion implantation, And an annealing step in which the implanted impurity is stored in the crystal lattice position and electrically activated. Here, the shallow impurity diffusion layer is formed by lowering the implantation energy and implanting impurities in the ion implantation step.

  In the annealing process after the ion implantation process, a rapid heat treatment method is used in which light is irradiated from a light source such as a lamp or a laser to the ion implanted substrate and rapidly heated to a high temperature of about 1000 ° C. In the rapid thermal processing method (RTA), only the substrate surface can be selectively heated, so that high-speed heating at about 100 ° C./second is possible, and short-time processing at about 10 seconds is possible.

  However, even when annealing is performed at a high temperature for a short time using RTA, the diffusion of impurities cannot be completely suppressed. Such impurity diffusion is acceptable if the impurity implantation layer is deep to some extent. However, for example, when the depth of the implantation layer is extremely shallow, such as about 50 nm, the amount of impurities diffused deeper than the depth of the implantation layer by heating cannot be ignored.

  This is because even when RTA is used, the substrate is heated at a depth that is equal to or greater than the ultra-shallow depth as described above. That is, the silicon crystal deeper than the implantation layer is excited by heating, and the impurity moves (diffuses) in the crystal. When the impurities are diffused and activated in this way, the substantial diffusion depth is increased to a significant level, and the reliability of the MOS is lowered, for example, the short channel effect is not prevented.

  As described above, in order to form an extremely shallow impurity diffusion layer, it is necessary to selectively heat (excite) only the silicon crystal in the extremely shallow region of the substrate surface. However, there has never been such a technique.

The present invention has been made in view of the above circumstances, and relates to a highly reliable semiconductor device manufacturing apparatus.
The present invention also relates to a semiconductor device manufacturing apparatus capable of forming an extremely shallow diffusion layer with high reliability.
Furthermore, the present invention relates to a semiconductor device manufacturing apparatus capable of selectively exciting a silicon crystal on a substrate surface.

In order to achieve the above object, a plasma processing apparatus according to the first aspect of the present invention provides:
A chamber;
A gas supply unit for supplying a predetermined gas to the chamber;
A planar antenna having a plurality of slits for introducing microwaves into the chamber;
A substrate holding part that is disposed to face the planar antenna and heats the substrate to be processed which has been previously doped with impurities;
A vacuum exhaust part for maintaining the pressure in the chamber in a range of 40 Pa to 0.13 kPa,
A plasma generation unit configured to generate plasma having an electron temperature of 0.7 eV to 2 eV by microwaves from the planar antenna unit from the gas supplied into the chamber by the gas supply unit;
Irradiating the plasma to be processed with the plasma generated by the plasma generation unit, and selectively exciting the atoms of the substrate to be processed at the depth of the impurity implantation layer by active species in the plasma , A control unit that activates the impurity doped in the substrate to be processed and suppresses the impurity diffused deeper than the depth of the implantation layer, and controls to form an impurity diffusion layer;
It is characterized by comprising.

  According to the present invention, a highly reliable semiconductor device manufacturing apparatus can be provided.

  A method and apparatus for manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings.

  According to the method for manufacturing a semiconductor device according to the embodiment of the present invention, for example, a p-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is manufactured. FIG. 1 shows the structure of a p-channel MOS (hereinafter referred to as pMOS) 11 manufactured using the method for manufacturing a semiconductor device of the present embodiment.

  As shown in FIG. 1, the pMOS 11 includes a silicon substrate 12, a gate insulating film 13, and a gate electrode 14.

  The silicon substrate 12 is an n-type substrate formed by epitaxial growth or the like. The silicon substrate 12 may be an SOI (Silicon On Insulator) substrate.

  The gate insulating film 13 is formed on the silicon substrate 12. The gate insulating film 13 includes a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a laminated film of these and a high dielectric constant film such as tantalum oxide. The gate insulating film 13 is provided with a thickness of 2 to 5 nm (20 to 50 mm), for example.

  The gate electrode 14 is stacked on the gate insulating film 13. The gate electrode 14 is made of polysilicon doped with impurities, aluminum, or the like. The gate electrode 14 is provided with a thickness of, for example, 0.1 μm to 0.3 μm (1000 to 3000 mm).

  A source region 15 and a drain region 16 are formed on both sides of the gate insulating film 13 in the surface region of the silicon substrate 12. The source region 15 and the drain region 16 are p-type impurity diffusion regions formed by introducing p-type impurities into the n-type silicon substrate 12.

  The source region 15 and the drain region 16 are connected to a source electrode and a drain electrode (not shown), respectively. When a predetermined voltage (gate voltage) is applied to the gate electrode 14, an inversion layer, that is, a channel (ch) is formed in the surface region of the silicon substrate 12. When a predetermined voltage is applied to the source electrode and the drain electrode, a current flows between the source region 15 and the drain region 16 through the channel (ch).

  Here, the impurity diffusion layers forming the source region 15 and the drain region 16 are each formed extremely shallow in the depth (thickness) direction of the substrate, for example, at a depth of 2 nm to 50 nm (20 to 500 mm) or less. Has been. The ultra-shallow impurity diffusion layer is formed by ion implantation of p-type impurities (for example, boron), ion implantation (impurity introduction) by plasma doping or the like, and subsequent annealing treatment. The annealing process is formed using microwave plasma using a radial line slot antenna (RLSA) described later.

  Next, a method for manufacturing the semiconductor device (pMOS 11) according to the embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows a configuration of a manufacturing apparatus 100 used for manufacturing a semiconductor device.
As shown in FIG. 2, the manufacturing apparatus 100 includes a cassette station 101 and a processing station 102.

  The cassette station 101 includes a cassette stage 103 and a transfer chamber 104. On the cassette stage 103, a cassette C capable of accommodating a predetermined number of semiconductor wafers (hereinafter referred to as wafers W) is placed. On the cassette stage 103, the cassette C that stores the unprocessed wafers W is placed, while the cassette C that stores the processed wafers W is unloaded from the cassette stage 103.

  In the transfer chamber 104, a pair of loader arms 105 and 106 are arranged. The loader arms 105 and 106 carry in the wafer W accommodated in the cassette C to the processing station 102 side, and carry out the processed wafer W from the processing station 102 side and accommodate it in the cassette C. The inside of the transfer chamber 104 is kept clean by downflow of clean air.

  The processing station 102 includes a vacuum platform 107, two load lock units 108 and 109, two doping units 110 and 111, and two annealing units 112 and 113.

  Each unit is connected to the periphery of the substantially octagonal vacuum platform 107 via a gate valve so as to be connected or disconnected. That is, the processing station 102 constitutes a cluster type system. The vacuum platform 107 includes an exhaust mechanism and can be depressurized to a predetermined vacuum state. Each unit isolated by the gate valve is provided with an exhaust mechanism, and an atmosphere independent of the vacuum platform 107 can be formed therein.

  In the center of the vacuum platform 107, a pair of transfer arms 114 and 115 are provided to transfer the wafer W between the units.

  The load lock units 108 and 109 are connected to the transfer chamber 104 of the cassette station 101 so as to be connected or disconnected. The load lock units 108 and 109 function as a wafer carry-in port to the processing station 102 and a wafer carry-out port. The loader arms 105 and 106 carry the wafers W accommodated in the cassette C on the cassette stage 103 into the load lock units 108 and 109. The loader arms 105 and 106 carry out the processed wafers W from the load lock units 108 and 109 and store them in the cassette C.

  The doping units 110 and 111 are configured by a general low energy ion implantation apparatus, a plasma doping apparatus, or the like. In the doping units 110 and 111, p-type impurities are selectively introduced into the silicon substrate 12 (wafer W) to form an impurity implantation layer.

Impurities are introduced in a self-aligned manner using the gate electrode 14 as a mask, for example. Impurity introduction is performed, for example, at a dose of 1 × 10 ^{13 to} 5 × 10 ¹⁵ cm ⁻² , for example, with a diffusion depth of ² nm to 50 nm (20 to 500 cm). As the p-type impurity, boron (B), indium (In), or the like can be used.

  The annealing units 112 and 113 are radial line slot antenna (RLSA) type plasma processing apparatuses. The annealing units 112 and 113 generate plasma of a processing gas using microwave energy, and anneal the surface of the silicon substrate 12 after doping with this plasma.

  FIG. 3 shows a cross-sectional configuration of the annealing units 112 and 113. As shown in FIG. 3, the annealing units 112 and 113 include a substantially cylindrical chamber 201. The chamber 201 is made of aluminum or the like.

  In the center of the chamber 201, a mounting table 202 for a wafer W, which is an object to be processed, is disposed. The mounting table 202 includes a temperature control unit (not shown), and the wafer W is heated to a predetermined temperature, for example, room temperature to 600 ° C. by the temperature control unit.

  The mounting table 54 has a circuit for applying a predetermined voltage. By this circuit, a bias voltage for accelerating ions in the plasma (for example, about −50 V to 0 V, preferably −20 V to 0V) is applied to the wafer W.

  A loading / unloading port 203 is provided on the side wall of the chamber 201 at substantially the same height as the upper surface of the mounting table 202. The loading / unloading port 203 is connected to the vacuum platform 107 via the gate valve 204. When the gate valve 204 is opened, the wafer W is loaded / unloaded via the loading / unloading port 203.

  One end of an exhaust pipe 205 is connected to the bottom of the chamber 201, and the other end is connected to an exhaust device 206 such as a vacuum pump. The inside of the chamber 201 during processing is set to 40 Pa to 0.13 kPa (30 mTorr to 1 Torr) by the exhaust device 206 or the like.

A gas supply pipe 207 is provided above the side portion of the chamber 201. The gas supply pipe 207 is connected to an argon (Ar) gas source 208 and a nitrogen (N ₂ ) gas source 209. The gas supply pipes 207 are equally arranged at, for example, 16 locations along the circumferential direction of the side wall of the chamber 201. By arranging in this way, the gas supplied from the gas supply pipe 207 is evenly supplied above the wafer W on the mounting table 202.

An opening 210 is provided in the upper part of the chamber 201. A window 211 is provided inside the opening 210. The window 211 is made of a transparent material such as quartz, SiO ₂ glass, Si ₃ N ₄ , NaCl, KCl, LiF, CaF ₂ , BaF ₂ , Al ₂ O ₃ , AlN, MgO, or polyethylene. Polyester, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide and other organic films and sheets.

  On the window 211, for example, a radial line slot antenna (hereinafter referred to as RLSA) 212 is provided. On the RLSA 212, a waveguide 214 connected to the high frequency power supply unit 213 is provided. The waveguide 214 includes a flat circular waveguide 215 having a lower end connected to the RLSA 212, a cylindrical waveguide 216 having one end connected to the upper surface of the circular waveguide 215, and an upper surface of the cylindrical waveguide 216. And a rectangular waveguide 218 having one end connected at right angles to the side surface of the coaxial waveguide converter 217 and the other end connected to the high-frequency power supply unit 213. Yes. The RLSA 212 and the waveguide 214 are made of a copper plate.

  A coaxial waveguide 219 is disposed inside the cylindrical waveguide 216. The coaxial waveguide 219 is made of a shaft member made of a conductive material, one end of which is connected to the substantially center of the upper surface of the RLSA 212 and the other end is connected coaxially to the upper surface of the cylindrical waveguide 216.

  FIG. 4 shows a plan view of the RLSA 212. As shown in FIG. 4, the RLSA 212 includes a plurality of slots 212a, 62a,... Provided on concentric circles on the surface. Each slot 212a is a substantially square through groove, and adjacent slots 212a are arranged so as to be orthogonal to each other to form a letter T. The length and arrangement interval of the slots 212a are determined according to the wavelength of the high frequency generated from the high frequency power supply unit 213.

  The high frequency power supply unit 213 generates, for example, a 2.45 GHz microwave with an output of 500 W to 5 kW. Microwaves generated from the high frequency power supply unit 213 are transmitted in the rectangular waveguide 218 in a rectangular mode. Further, the microwave is converted from the rectangular mode to the circular mode by the coaxial waveguide converter 217 and transmitted to the cylindrical waveguide 216 in the circular mode. The microwave is further transmitted in a state of being expanded by the circular waveguide 215 and is radiated from the slot 212a of the RLSA 212. The emitted microwave passes through the window 211 and is introduced into the chamber 201.

The inside of the chamber 201 is set to a predetermined vacuum pressure, and a mixed gas of Ar and N ₂ is, for example, Ar / N ₂ = 2000 (sccm): 200 (sccm) from the gas supply pipe 207. To be supplied. Here, the flow rate ratio may be Ar / N ₂ = 2000: 20, 1000/100.

  High frequency energy is transmitted to the mixed gas in the chamber 201 by the microwave transmitted through the window 211, and high frequency plasma is generated. At this time, since microwaves are radiated from the numerous slots 212a of the RLSA 212, high-density plasma is generated. Here, the active species in the plasma formed using the RLSA 212 has an electron temperature of about 0.7 to 2 eV. Thus, according to the RLSA 212, plasma active species having relatively moderate activity are generated.

  The wafer W is annealed by exposure to the generated high density plasma. That is, active species in the generated plasma, in particular, Ar ions contact and collide with silicon atoms on the surface of the wafer W to give energy to the silicon atoms on the substrate surface. The applied energy is transferred from silicon atoms on the surface of the silicon substrate 12 to silicon atoms located at a deeper position. Such energy transfer excites silicon atoms (crystals) with a predetermined depth.

  Similarly, the silicon crystal is excited in the impurity implantation layer. Excitation causes rearrangement (recrystallization) of the silicon crystals disturbed by implantation (doping). Thereby, lattice defects in the implanted layer are reduced or eliminated.

  At this time, simultaneously with the rearrangement of the crystal lattice, impurities introduced by doping (such as B) that are not arranged at the predetermined crystal lattice position are also accommodated at the crystal lattice position and activated as dopants. . Thereby, an impurity diffusion layer (source region 15 and drain region 16) having a desired electrical characteristic stably can be obtained.

  Here, as described above, the plasma active species generated using RLSA has a relatively low energy. For this reason, damage to the surface of the silicon substrate 12 can be avoided. The energy imparted to the silicon crystal by the active species is consumed by the rearrangement of the silicon crystal in the transmission process, and is not transmitted to the silicon atoms at a depth greater than a predetermined depth from the surface.

  From this, the plasma generation conditions are appropriately adjusted to selectively excite silicon atoms having a depth of the implanted layer (about 50 nm), while atoms having a depth greater than that are not excited. By generating the active species, it is possible to suppress the diffusion of impurities at a depth greater than that of the implanted layer.

  Hereinafter, a method of manufacturing the semiconductor device according to the present embodiment will be described with reference to FIG.

  First, a cassette C containing a predetermined number of wafers W is placed on the cassette stage 103. The wafer W is formed by laminating a gate insulating film 13 and a gate electrode 14 on a silicon substrate 12. The loader arms 105 and 106 take out the wafer W from the cassette C and carry it into the load lock units 108 and 109.

  After loading, the interiors of the load lock units 108 and 109 are airtight, and the pressure is close to the interior of the vacuum platform 107. Thereafter, the load lock units 108 and 109 are opened to the vacuum platform side. Next, the transfer arms 114 and 115 carry the wafer W out of the load lock units 108 and 109.

  The transfer arms 114 and 115 carry the wafer W into the doping units 110 and 111. After carrying in, the gate valve is closed, and the doping units 110 and 111 are set to a predetermined pressure. Thereafter, impurities are introduced into the wafer W in a self-aligning manner using the gate electrode 14 as a mask. Thereby, the source region 15 and the drain region 16 are formed in the vicinity of the gate electrode 14. After the doping is completed, the inside of the doping units 110 and 111 is brought to the original pressure, and the gate valve is opened. The transfer arms 114 and 115 carry out the processed wafer W.

  Next, the wafer W is carried into the annealing units 112 and 113. After loading, the gate valve is closed and the annealing units 112 and 113 are set to a predetermined pressure. In the annealing units 112 and 113, the wafer W is subjected to an annealing process using RLSA plasma. Thereby, the diffusion of impurities is suppressed, and the surface region of the wafer W is stabilized in a state where the depth of the impurity diffusion layer is kept extremely shallow. After the annealing process is completed, the inside of the annealing units 112 and 113 is set to the original pressure, and the gate valve is opened. The transfer arms 114 and 115 carry out the processed wafer W.

  The annealed wafer W is transferred into the load lock units 108 and 109. Thereafter, the wafer W is accommodated in the cassette 74 in accordance with the reverse process of the loading into the load lock units 108 and 109. A cassette C containing a predetermined number of processed wafers W is unloaded from the semiconductor manufacturing apparatus 100. The processed wafer W is then subjected to an insulating film formation process and a gate / drain electrode formation process. As described above, the manufacturing process of the pMOS 11 is completed.

  As described above, in the embodiment of the present invention, the plasma diffusion species generated using the RLSA 212 is brought into contact with the surface of the silicon substrate 12 to anneal the impurity diffusion layer. The energy of the generated active species is energy that does not damage the surface of the silicon substrate 12 and that selectively excites only silicon atoms that are slightly deeper than the depth of the impurity diffusion layer.

  As described above, in the annealing of the impurity diffusion layer using the RLSA plasma, the silicon crystal having a predetermined depth can be selectively excited from the substrate surface, and the impurity diffusion can be suppressed low. Therefore, even in the extremely shallow impurity diffusion layer, the depth is kept shallow, and a highly reliable pMOS 11 in which the short channel effect is prevented is obtained.

  The present invention is not limited to the description of the above embodiment, and its application and modification are arbitrary.

  In the above embodiment, the pMOS has been described as an example, but an n-channel MOS may be used. In this case, if an n-type impurity such as arsenic, phosphorus, antimony or the like is used as a dopant, an n-type impurity diffusion layer can be formed extremely shallowly. Further, it may be a MIS (Metal Insulator Semiconductor) FET, a CMOS (Complementary MOS) FET, or the like.

  In the above embodiment, the semiconductor manufacturing apparatus 100 includes two doping units 110 and 111 and two plasma annealing units 112 and 113, respectively. However, the number and arrangement of units constituting the semiconductor manufacturing apparatus 100 are arbitrary.

In the above embodiment, the annealing process in the annealing units 112 and 113 uses a mixed gas of Ar and N ₂ . However, instead of Ar, krypton (Kr), xenon (Xe) or the like may be used alone or in combination.
Further, O ₂ may be used instead of N ₂ . _{It may} also be added H 2, _{O 2} or the like. In particular, when H ₂ is added, H radicals generated from H ₂ are combined with Si dangling bonds to stabilize the formed silicon oxide film and improve the film quality.

It is sectional drawing of the semiconductor device manufactured by the manufacturing method of the semiconductor device which concerns on embodiment of this invention. It is a figure which shows the structure of the manufacturing apparatus of the semiconductor device which concerns on embodiment of this invention. It is a figure which shows the structure of the annealing unit which concerns on embodiment of this invention. It is a figure which shows the structure of the planar antenna member (RLSA) which concerns on embodiment of this invention.

Explanation of symbols

11 pMOS
12 Silicon substrate 13 Gate insulating film 14 Gate electrode 15 Source region 16 Drain region 100 Manufacturing apparatus 101 Cassette station 102 Processing station 111, 111 Doping unit 112, 113 Annealing unit 212 RLSA

Claims (1)

A chamber;
A gas supply unit for supplying a predetermined gas to the chamber;
A planar antenna having a plurality of slits for introducing microwaves into the chamber;
A substrate holding part that is disposed to face the planar antenna and heats the substrate to be processed which has been previously doped with impurities;
A vacuum exhaust part for maintaining the pressure in the chamber in a range of 40 Pa to 0.13 kPa,
A plasma generation unit configured to generate plasma having an electron temperature of 0.7 eV to 2 eV by microwaves from the planar antenna unit from the gas supplied into the chamber by the gas supply unit;
Irradiating the plasma to be processed with the plasma generated by the plasma generation unit, and selectively exciting the atoms of the substrate to be processed at the depth of the impurity implantation layer by active species in the plasma , A control unit that activates the impurity doped in the substrate to be processed and suppresses the impurity diffused deeper than the depth of the implantation layer, and controls to form an impurity diffusion layer;
A plasma processing apparatus comprising:

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