WO2014148130A1 - 炭化珪素半導体装置およびその製造方法 - Google Patents
炭化珪素半導体装置およびその製造方法 Download PDFInfo
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- WO2014148130A1 WO2014148130A1 PCT/JP2014/052542 JP2014052542W WO2014148130A1 WO 2014148130 A1 WO2014148130 A1 WO 2014148130A1 JP 2014052542 W JP2014052542 W JP 2014052542W WO 2014148130 A1 WO2014148130 A1 WO 2014148130A1
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- insulating film
- side wall
- silicon carbide
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- semiconductor layer
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- H01L21/0445—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising crystalline silicon carbide
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- H01L21/045—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising crystalline silicon carbide passivating silicon carbide surfaces
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- H01L29/423—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions not carrying the current to be rectified, amplified or switched
- H01L29/42312—Gate electrodes for field effect devices
- H01L29/42316—Gate electrodes for field effect devices for field-effect transistors
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- H01L29/511—Insulating materials associated therewith with a compositional variation, e.g. multilayer structures
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- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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Definitions
- the present invention relates to a silicon carbide semiconductor device and a method for manufacturing the same, and more particularly to a silicon carbide semiconductor device having a trench and a method for manufacturing the same.
- Patent Document 1 JP-A-7-326755 discloses a trench gate type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) using a silicon carbide substrate. According to this publication, the thickness of the gate thermal oxide film on the bottom surface of the trench is larger than the thickness of the gate thermal oxide film on the side surface of the trench.
- MOSFET Metal Oxide Semiconductor Field Effect Transistor
- a smaller gate electrode capacity is desired.
- MISFET Metal Insulator Semiconductor Field Effect Transistor
- the gate electrode capacitance can be reduced to some extent by increasing the thickness of the bottom surface of the gate insulating film (gate thermal oxide film), a smaller gate electrode capacitance is desired. It is.
- the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a silicon carbide semiconductor device having a small gate electrode capacity and a method for manufacturing the same.
- the silicon carbide semiconductor device of the present invention has a silicon carbide substrate, a gate insulating film, a gate insulating film, and a gate electrode.
- the silicon carbide substrate is provided on the first semiconductor layer having the first conductivity type, the second semiconductor layer having the second conductivity type provided on the first semiconductor layer, and the second semiconductor layer. And a third semiconductor layer having a first conductivity type and separated from the first semiconductor layer by the second semiconductor layer.
- the silicon carbide substrate is provided with a trench.
- the trench includes a bottom surface made of the first semiconductor layer and a side wall surface having first to third side surfaces made of the first to third semiconductor layers.
- the gate insulating film is provided on the trench.
- the gate insulating film includes a first insulating film that directly covers each of the sidewall surface and the bottom surface, and a second insulating film provided on the first insulating film.
- the first insulating film has a first bottom portion located on the bottom surface and a first sidewall portion located on the sidewall surface.
- the first side wall portion has first to third regions located on the first to third side surfaces, respectively.
- the second insulating film has a second bottom portion located on the first bottom portion and a second sidewall portion located on the first sidewall portion.
- the second side wall portion has one end connected to the second bottom portion, and the other end located on one of the first and second regions and away from the third region.
- the gate electrode is provided on the trench via the gate insulating film.
- the manufacturing method of the silicon carbide semiconductor device of this invention has the following processes.
- a silicon carbide substrate including a third semiconductor layer having a first conductivity type separated from the first semiconductor layer by the layer is prepared.
- a trench is formed in the silicon carbide substrate.
- the trench includes a bottom surface made of the first semiconductor layer and a side wall surface having first to third side surfaces made of the first to third semiconductor layers.
- a first insulating film that directly covers each of the side wall surface and the bottom surface is formed.
- the first insulating film has a first bottom portion located on the bottom surface and a first sidewall portion located on the sidewall surface.
- the first side wall portion has first to third regions located on each of the first to third side surfaces.
- a silicon film is formed on the first insulating film.
- the silicon film has a second bottom portion located on the first bottom portion and a second sidewall portion located on the first sidewall portion.
- the second side wall portion has one end connected to the second bottom portion, and the other end located on one of the first and second regions and away from the third region.
- a second insulating film is formed by oxidizing the silicon film.
- the first and second insulating films constitute a gate insulating film.
- a gate electrode is formed on the trench through the gate insulating film.
- the gate electrode capacitance can be reduced.
- FIG. 1 is a partial cross sectional view schematically showing a configuration of a silicon carbide semiconductor device in a first embodiment of the present invention.
- FIG. 2 is a perspective view schematically showing a shape of a silicon carbide substrate included in the silicon carbide semiconductor device of FIG. 1.
- FIG. 3 is a diagram illustrating the configuration of FIG. 2 in more detail, and is a diagram in which a region of a second conductivity type is hatched for easy viewing of the diagram.
- FIG. 2 is an enlarged view of FIG. 1, in particular, explaining the components of the first insulating film.
- FIG. 2 is an enlarged view of FIG. 1, particularly illustrating a dimension of a gate insulating film.
- FIG. 8 is a partial cross sectional view schematically showing a first step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 8 is a partial cross sectional view schematically showing a second step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 8 is a partial cross sectional view schematically showing a third step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 8 is a partial cross sectional view schematically showing a fourth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 8 is a partial cross sectional view schematically showing a fifth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 8 is a partial cross sectional view schematically showing a sixth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 8 is a partial cross sectional view schematically showing a seventh step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 12 is a partial cross sectional view schematically showing an eighth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 12 is a partial cross sectional view schematically showing a ninth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 12 is a partial cross sectional view schematically showing a tenth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 12 is a partial cross sectional view schematically showing an eleventh step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 12 is a partial cross sectional view schematically showing a twelfth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1.
- FIG. 14 is a partial cross sectional view schematically showing a thirteenth step of the method for manufacturing the silicon carbide semiconductor device of FIG. 1. It is a fragmentary sectional view which shows schematically the structure of the silicon carbide semiconductor device in Embodiment 2 of this invention. It is a fragmentary sectional view which shows schematically the structure of the silicon carbide semiconductor device in Embodiment 3 of this invention.
- FIG. 3 is a diagram showing a crystal structure of a (000-1) plane in polytype 4H hexagonal crystal.
- FIG. 23 is a view showing a crystal structure of a (11-20) plane along line XXIII-XXIII in FIG.
- FIG. 22 is a view showing a crystal structure in the vicinity of the surface of the composite surface in FIG. 21 in the (11-20) plane.
- FIG. 22 is a diagram when the composite surface of FIG. 21 is viewed from the (01-10) plane.
- FIG. 3 is a diagram showing a crystal structure of a (000-1) plane in polytype 4H hexagonal crystal.
- FIG. 23 is a view showing a crystal structure of a (11-20) plane along line XXIII-XXIII in FIG.
- FIG. 22 is a view showing a crystal structure in the vicinity of the surface of the composite surface in FIG. 21 in the (11-20) plane.
- FIG. 22 is a diagram when the composite surface of FIG. 21 is viewed from the (01
- FIG. 5 is a graph showing an example of a relationship between a channel surface and a (000-1) plane viewed macroscopically and channel mobility when a thermal etching is performed and when it is not performed. It is. It is a graph which shows an example of the relationship between the angle between a channel direction and the ⁇ 0-11-2> direction, and channel mobility. It is a figure which shows the modification of FIG. And the capacitance C gd between the gate electrode and the drain electrode is a diagram showing the relationship between the voltage V DS between the drain electrode and the source electrode.
- Silicon carbide semiconductor devices 501 to 503 have silicon carbide substrate 100, gate insulating film 200, and gate electrode 230.
- the silicon carbide substrate 100 includes a first semiconductor layer 121 having a first conductivity type, a second semiconductor layer 122 having a second conductivity type provided on the first semiconductor layer 121, and a second semiconductor.
- a third semiconductor layer 123 provided on the layer 122 and separated from the first semiconductor layer 121 by the second semiconductor layer 122 and having the first conductivity type.
- Silicon carbide substrate 100 is provided with a trench TR.
- Trench TR includes a bottom surface BT made of first semiconductor layer 121 and side wall surface SW having first to third side faces SW1 to SW3 made of first to third semiconductor layers 121 to 123, respectively.
- Gate insulating film 200 is provided on trench TR.
- the gate insulating film 200 includes a first insulating film 201 that directly covers each of the side wall surface SW and the bottom surface BT, and a second insulating film 202 provided on the first insulating film 201.
- the first insulating film 201 has a first bottom portion 201B located on the bottom surface BT and a first sidewall portion 201S located on the sidewall surface SW.
- the first side wall portion 201S includes first to third regions 201a to 201c located on the first to third side surfaces SW1 to SW3, respectively.
- the second insulating film 202 has a second bottom 202B located on the first bottom 201B and a second sidewall 202S located on the first sidewall 201S.
- the second side wall portion 202S has one end E1 connected to the second bottom portion 202B and the other end E2 located on one of the first and second regions 201a and 201b and separated from the third region 201c. And have.
- Gate electrode 230 is provided on trench TR through gate insulating film 200.
- second insulating film 202 that forms gate insulating film 200 together with first insulating film 201 is not only on first bottom portion 201 B of first insulating film 201.
- the first insulating film 201 is also provided on the first sidewall portion 201S.
- gate insulating film 200 has a greater thickness not only on bottom surface BT of trench TR but also on side wall surface SW that forms corner portion CR together with bottom surface BT in the vicinity of bottom surface BT. Therefore, the gate electrode capacitance can be further reduced as compared with the case where the gate insulating film 200 is thickened only on the bottom surface BT of the trench.
- the other end E2 of the second side wall 202S may be located on the boundary between the first region 201a and the second region 201b.
- the second side wall portion 202S is extended to the maximum extent within a range that does not cover the second region 201b constituting the channel surface. Therefore, the gate electrode capacitance can be effectively reduced within a range that hardly affects the channel characteristics.
- the other end E2 of the second side wall portion 202S may be located on the first region 201a away from the second region 201b.
- the second side wall 202S is extended within a range not approaching the second region 201b constituting the channel surface. Therefore, the gate electrode capacitance can be reduced within a range that does not affect the channel characteristics.
- the other end E2 of the second side wall portion 202S may be located on the second region 201b apart from the third region 201c.
- the second side wall 202S is further extended as compared with the case where the second side wall 202S is provided only on the first region 201a. Further, the second side wall portion 202S is provided apart from the boundary between the second region 201b and the third region 201c, which has a large influence on the channel characteristics. Therefore, the gate electrode capacitance can be more effectively reduced while suppressing the influence on the channel characteristics.
- the second semiconductor layer 122 has a depth position DP where the impurity concentration reaches a peak, and the other end E2 of the second side wall 202S is located deeper than the depth position DP. May be.
- the second side wall 202S is further extended as compared with the case where the second side wall 202S is provided only on the first region 201a. Further, the second side wall portion 202S is provided apart from the depth position DP that has a great influence on the channel characteristics. Therefore, it is possible to more effectively reduce the gate electrode capacitance while further suppressing the influence on the channel characteristics.
- the other end E2 of the second side wall portion 202S may have an inclination angle AG of less than 70 degrees with respect to the first side wall portion 201S.
- each of the first and second insulating films 201 and 202 has the first and second carbon atom concentrations, and the second carbon atom concentration is the first carbon atom concentration. It may be smaller than the carbon atom concentration.
- the second insulating film 202 has high dielectric breakdown resistance due to low carbon atom concentration. Therefore, silicon carbide semiconductor devices 501 to 503 have a large breakdown voltage.
- the first carbon atom concentration may be greater than 1 ⁇ 10 15 cm ⁇ 3 and the second carbon atom concentration may be less than 1 ⁇ 10 15 cm ⁇ 3 .
- the carbon atom concentration of the second insulating film 202 is sufficiently lowered. Therefore, the breakdown voltage of silicon carbide semiconductor devices 501 to 503 can be further increased.
- the second insulating film 202 may be made of at least one of silicon oxide, silicon nitride, and phosphosilicate glass.
- the breakdown voltage of silicon carbide semiconductor devices 501 to 503 can be further increased.
- the second insulating film 202 may be a thermal oxide film that contains silicon and does not contain carbon.
- the method for manufacturing silicon carbide semiconductor devices 501 to 503 includes the following steps.
- Silicon carbide substrate 100 including a third semiconductor layer 123 having a first conductivity type and separated from first semiconductor layer 121 by second semiconductor layer 122 is prepared.
- Trench TR is formed in silicon carbide substrate 100.
- Trench TR includes a bottom surface BT made of first semiconductor layer 121 and side wall surface SW having first to third side faces SW1 to SW3 made of first to third semiconductor layers 121 to 123, respectively.
- a first insulating film 201 that directly covers each of the side wall surface SW and the bottom surface BT is formed.
- the first insulating film 201 has a first bottom portion 201B located on the bottom surface BT and a first sidewall portion 201S located on the sidewall surface SW.
- the first side wall portion 201S includes first to third regions 201a to 201c located on the first to third side surfaces SW1 to SW3, respectively.
- a silicon film 302 is formed on the first insulating film 201.
- the silicon film 302 has a second bottom portion 302B located on the first bottom portion 201B and a second side wall portion 302S located on the first side wall portion 201S.
- the second side wall portion 302S has one end E1 connected to the second bottom portion 302B and the other end E2 located on one of the first and second regions 201a and 201b and separated from the third region 201c. And have.
- the second insulating film 202 is formed by oxidizing the silicon film 302.
- the first and second insulating films 201 and 202 constitute the gate insulating film 200.
- Gate electrode 230 is formed on trench TR via gate insulating film 200.
- the second insulating film 202 that forms the gate insulating film 200 together with the first insulating film 201 is not only on the first bottom 201B of the first insulating film 201, but also on the first insulating film 201.
- the insulating film 201 is also provided on the first side wall portion 201S.
- the gate insulating film 200 has a larger thickness not only on the bottom surface BT of the trench but also on the side wall surface SW surface that forms the corner CR together with the bottom surface BT in the vicinity of the bottom surface BT. Therefore, the gate electrode capacitance can be further reduced as compared with the case where the gate insulating film 200 is thickened only on the bottom surface BT of the trench.
- the step of forming the second insulating film 202 by oxidizing the silicon film 302 may be performed at 800 ° C. or higher and 1150 ° C. or lower.
- the surface roughness of the silicon film 302 can be suppressed by oxidizing the silicon film 302 at 800 ° C. or higher. Further, by oxidizing the silicon film at 1150 ° C. or lower, it is possible to suppress an increase in the vapor pressure of the second insulating film 202 made of silicon dioxide formed by oxidizing the silicon film 302. As a result, the shape of the second insulating film 202 can be maintained.
- the step of forming the second insulating film 202 is performed so that the angle AG of the other end E2 of the second side wall portion 202S with respect to the first side wall portion 201S becomes smaller.
- a step of heating the side wall portion 202 ⁇ / b> S may be included.
- the step of heating the second side wall 202S may be performed at 1300 ° C. or higher and 1400 ° C. or lower.
- the angle AG of the other end E2 can be made sufficiently small without using an excessively high temperature.
- a vertical MOSFET 501 (silicon carbide semiconductor device) of the present embodiment includes an epitaxial substrate 100 (silicon carbide substrate), a gate insulating film 200, a gate electrode 230, an interlayer insulating film 203, A source electrode 221, a drain electrode 211, a source wiring 222, and a protective electrode 212 are included.
- Epitaxial substrate 100 is made of silicon carbide, and has single crystal substrate 110 and an epitaxial layer provided thereon.
- Single crystal substrate 110 has n-type (first conductivity type).
- the plane orientation (hklm) of one main surface (upper surface in FIG. 1) of single crystal substrate 110 preferably has a negative m, more preferably approximately (000-1).
- the epitaxial layer includes an n ⁇ layer 121 (first semiconductor layer), a p-type body layer 122 (second semiconductor layer), an n region 123 (third semiconductor layer), and a contact region 124.
- Silicon carbide of epitaxial substrate 100 preferably has a hexagonal crystal structure, and more preferably has polytype 4H.
- the n ⁇ layer 121 has an n-type by adding a donor.
- the donor is preferably added to the n ⁇ layer 121 not by ion implantation but by impurity addition during the epitaxial growth of the n ⁇ layer 121.
- the donor concentration of n ⁇ layer 121 is preferably lower than the donor concentration of single crystal substrate 110.
- the donor concentration of the n ⁇ layer 121 is preferably 1 ⁇ 10 15 cm ⁇ 3 or more and 5 ⁇ 10 16 cm ⁇ 3 or less, for example, 8 ⁇ 10 15 cm ⁇ 3 .
- the p-type body layer 122 is provided on the n ⁇ layer 121 and has p-type (second conductivity type) by adding an acceptor.
- the acceptor concentration of p-type body layer 122 is, for example, 1 ⁇ 10 18 cm ⁇ 3 .
- N region 123 has n type. N region 123 is provided on p type body layer 122 and is separated from n ⁇ layer 121 by p type body layer 122. Contact region 124 has a p-type. Contact region 124 is formed on part of p type body layer 122 so as to be connected to p type body layer 122.
- epitaxial substrate 100 is provided with a trench TR.
- Trench TR has side wall surface SW passing through n region 123 and p-type body layer 122 to n ⁇ layer 121, and bottom surface BT formed of n ⁇ layer 121.
- Sidewall surface SW includes channel surface CH (FIG. 3) on p-type body layer 122.
- Bottom surface BT is a flat surface substantially parallel to the main surface of epitaxial substrate 100.
- the fact that the epitaxial substrate 100 has the trench TR corresponds to the fact that the epitaxial layer is partially removed on the upper surface of the single crystal substrate 110. In this embodiment, a large number of mesa structures are formed on the upper surface of single crystal substrate 110.
- the mesa structure has a hexagonal shape at the top and bottom, and the side walls thereof are inclined with respect to the top surface of the single crystal substrate 110.
- the trench TR expands toward the opening side.
- sidewall surface SW has a predetermined crystal plane (also referred to as a special plane), particularly on p-type body layer 122. Details of the special surface will be described later.
- side wall surface SW has first to third side surfaces SW1 to SW3 formed of n ⁇ layer 121, p type body layer 122, and n region 123, respectively.
- Gate insulating film 200 is provided on trench TR. Gate insulating film 200 separates epitaxial substrate 100 and gate electrode 230 in trench TR.
- the gate insulating film 200 includes a first insulating film 201 that directly covers each of the side wall surface SW and the bottom surface BT, and a second insulating film 202 provided on the first insulating film 201.
- Each of the first and second insulating films 201 and 202 has first and second carbon atom concentrations.
- the second carbon atom concentration may be smaller than the first carbon atom concentration.
- the first carbon atom concentration may be greater than 1 ⁇ 10 15 cm ⁇ 3 .
- the second carbon atom concentration may be less than 1 ⁇ 10 15 cm ⁇ 3 and may be substantially zero.
- the first insulating film 201 has a first bottom portion 201B located on the bottom surface BT and a first sidewall portion 201S located on the sidewall surface SW.
- the first side wall portion 201S has first to third regions 201a to 201c located on the first to third side surfaces SW1 to SW3, respectively.
- the first insulating film 201 is preferably an oxide film, and more preferably obtained by thermally oxidizing the surface of the trench TR of the epitaxial substrate 100.
- second insulating film 202 has a portion located on corner portion CR (FIG. 1) formed by bottom surface BT and side wall surface SW through first insulating film 201.
- the second insulating film 202 includes a second bottom portion 202B located on the first bottom portion 201B, and a second sidewall portion 202S located on the first sidewall portion 201S.
- the second side wall portion 202S is located on one end E1 connected to the second bottom portion 202B and one of the first and second regions 201a and 201b (FIG. 4) and is away from the third region.
- the other end E2 is located on the second region 201b away from the third region 201c.
- the other end E2 has an inclination angle AG (FIG. 5) with respect to the first side wall 201S.
- the inclination angle AG is an angle formed by the tip portion of the surface of the other end E2 and the portion of the surface of the first side wall portion 201S that is in contact with the other end E2.
- the inclination angle AG is preferably less than 70 degrees.
- the second semiconductor layer 122 may have a depth position DP (FIG. 5) where the impurity concentration reaches a peak. In this case, the other end E2 is preferably located deeper than the depth position DP.
- the second insulating film 202 may be made of at least one of silicon oxide, silicon nitride, and phosphosilicate glass.
- the second insulating film 202 may be a thermal oxide film that contains silicon and does not contain carbon, and is made of, for example, SiO 2 .
- Gate insulating film 200 includes a portion having first and second insulating films 201 and 202 on bottom surface BT of trench TR, and this portion has thickness d 0 .
- Gate insulating film 200 has a portion having first insulating film 201 and not having second insulating film 202 on sidewall surface SW of trench TR, that is, a portion made only of first insulating film 201. This part has a thickness d 1 .
- the gate insulating film 200 includes a portion having first and second insulating films 201 and 202 on the first side surface SW1 side wall surface SW of the trench TR, this portion has a thickness d 2.
- d 2 > d 1 ⁇ 1.5 is satisfied.
- d 2 ⁇ d 1 ⁇ 5 is satisfied.
- d 0 > d 1 is satisfied.
- d 0 ⁇ d 2 is satisfied.
- the gate electrode 230 is provided in the trench TR. Specifically, the gate electrode 230 is provided on the trench TR through the gate insulating film 200. The gate electrode 230 is in contact with the second region 201 b of the first insulating film 201. The upper surface of the gate electrode 230 is substantially the same height as the upper surface of the portion of the gate insulating film 200 located on the upper surface of the n region 123.
- the interlayer insulating film 203 is provided so as to cover a portion of the gate insulating film 200 that extends to the upper surface of the n region 123 and the gate electrode 230.
- the source electrode 221 passes through the interlayer insulating film 203 and is in contact with each of the n region 123 and the contact region 124.
- the source wiring 222 is provided on the source electrode 221 and the interlayer insulating film 203 so as to be in contact with the source electrode 221.
- Drain electrode 211 is provided on the surface of epitaxial substrate 100 opposite to the surface on which trench TR is provided.
- the protective electrode 212 covers the drain electrode 211.
- n ⁇ layer 121 is formed on single crystal substrate 110 by epitaxial growth.
- This epitaxial growth is performed by a CVD (Chemical Vapor Deposition) method using, for example, a mixed gas of silane (SiH 4 ) and propane (C 3 H 8 ) as a source gas and using, for example, hydrogen gas (H 2 ) as a carrier gas.
- CVD Chemical Vapor Deposition
- H 2 hydrogen gas
- p type body layer 122 on n ⁇ layer 121 and n region 123 on p type body layer 122 are formed.
- ion implantation is performed on the upper surface of n ⁇ layer 121.
- an acceptor such as aluminum (Al) is ion-implanted.
- a donor such as phosphorus (P) is ion-implanted.
- epitaxial substrate 100 having n ⁇ layer 121, p type body layer 122, and n region 123 is formed.
- epitaxial growth may be used with the addition of impurities.
- the contact region 124 is formed by ion implantation.
- activation heat treatment for activating the impurities added by ion implantation is performed.
- the temperature of this heat treatment is preferably 1500 ° C. or higher and 1900 ° C. or lower, for example, about 1700 ° C.
- the heat treatment time is, for example, about 30 minutes.
- the atmosphere of the heat treatment is preferably an inert gas atmosphere, for example, an Ar atmosphere. Silicon carbide substrate 100 is prepared as described above.
- a mask 401 having an opening that partially exposes the n region 123 is formed on the epitaxial substrate 100.
- the opening is formed corresponding to the position of trench TR (FIG. 1).
- a silicon oxide film formed by thermal oxidation can be used as the mask 401.
- n region 123, p type body layer 122, and part of n ⁇ layer 121 are removed by etching.
- etching method for example, reactive ion etching (RIE), particularly inductively coupled plasma (ICP) RIE can be used.
- ICP-RIE using SF 6 or a mixed gas of SF 6 and O 2 as a reaction gas can be used.
- the epitaxial substrate 100 is etched using the mask 401. Specifically, thermal etching is performed on the epitaxial substrate 100 on the inner surface SV of the recess TQ.
- the thermal etching can be performed, for example, by heating the epitaxial substrate 100 in an atmosphere containing a reactive gas having at least one kind of halogen atom.
- the at least one or more types of halogen atom includes at least one of a chlorine (Cl) atom and a fluorine (F) atom.
- This atmosphere is, for example, Cl 2 , BCL 3 , SF 6 , or CF 4 .
- thermal etching is performed using a mixed gas of chlorine gas and oxygen gas as a reaction gas and a heat treatment temperature of, for example, 700 ° C. or more and 1000 ° C. or less.
- the reaction gas may contain a carrier gas in addition to the chlorine gas and the oxygen gas.
- the carrier gas for example, nitrogen (N 2 ) gas, argon gas, helium gas or the like can be used.
- the SiC etching rate is, for example, about 70 ⁇ m / hour.
- the mask 401 made of silicon oxide has a very high selectivity with respect to SiC, so that it is not substantially etched during the etching of SiC.
- trench TR is formed in silicon carbide substrate 100 by the thermal etching described above.
- epitaxial substrate 100 is etched so as to be side-etched from the opening of mask 401 as indicated by arrow SE. Further, during this thermal etching, a special surface is self-formed on the side wall surface SW of the trench TR, particularly on the portion made of the p-type body layer 122.
- a first insulating film 201 that directly covers each of the side wall surface SW and the bottom surface BT is formed.
- the first insulating film 201 has a portion directly located on the bottom surface BT and a portion directly located on the side wall surface SW.
- the formation of the first insulating film 201 can be performed by thermal oxidation of the bottom surface BT of the trench TR and the side wall surface SW.
- a silicon film 302 is formed on the first insulating film 201.
- the formation of the silicon film 302 can be performed by, for example, a chemical vapor deposition (CVD) method.
- CVD chemical vapor deposition
- a resist layer 402 is formed on the silicon film 302 so as to fill the trench TR with the first insulating film 201 and the silicon film 302 interposed therebetween.
- the resist layer 402 can be formed by applying a resist solution.
- a part of the resist layer 402 and the silicon film 302 is etched. This etching can be performed without using an etching mask. That is, it can be performed by so-called etch back.
- the resist layer 402 and the silicon film 302 remain on the bottom surface BT so as to fill only a part of the trench TR by the above etching.
- the silicon film 302 has a second bottom portion 302B located on the first bottom portion 201B and a second side wall portion 302S located on the first side wall portion 201S.
- the second side wall portion 302S has one end E1 connected to the second bottom portion 302B and the other end E2 located on the second region 201b and away from the third region 201c.
- the resist layer 402 is removed (FIG. 14).
- the exposed portion of the first insulating film 201 that is not covered by the silicon film 302 is removed by etching (FIG. 15).
- the trench TR provided with the first insulating film 201 and the silicon film 302 is thermally oxidized.
- the silicon film 302 and the exposed portion of the sidewall surface SW of the trench TR are thermally oxidized.
- Silicon film 302 is thermally oxidized at, for example, 800 ° C. or more and 1150 ° C. or less.
- the second insulating film 202 is formed from the silicon film 302 (FIG. 16).
- the first and second insulating films 201 and 202 constitute the gate insulating film 200.
- the silicon film 302 is thermally oxidized at, for example, 950 ° C. or more and 1100 ° C. or less.
- the silicon film 302 is oxidized at a temperature lower than 950 ° C.
- stress relaxation due to the viscous flow of the silicon dioxide film formed by oxidizing the silicon film 302 does not work, so silicon near the grain boundary moves to the surface side, It is considered that crystal grains grow on the surface of the silicon film 302 to generate protrusions. Therefore, by oxidizing the silicon film 302 at 950 ° C. or higher, the formation of the protrusions can be suppressed, so that the surface roughness of the second insulating film 202 can be effectively suppressed.
- the silicon film 302 is oxidized at a temperature higher than 1100 ° C.
- the first insulating film 201 made of silicon dioxide and the silicon film 302 cause a chemical reaction to form silicon oxide, so that the shape of the second insulating film 202 is changed. It becomes difficult to maintain. Therefore, the shape of the second insulating film 202 can be effectively maintained by suppressing the increase in the vapor pressure of silicon oxide by oxidizing the silicon film 302 at 1100 ° C. or lower.
- the second sidewall 202S is heated at a sufficient temperature, thereby reducing the angle AG (FIG. 5).
- the heating temperature is preferably 1300 ° C. or higher and 1400 ° C. or lower.
- a gate electrode 230 is formed on the trench TR with the gate insulating film 200 interposed therebetween.
- the formation method of the gate electrode 230 can be performed by, for example, film formation of a conductor or doped polysilicon and CMP (Chemical Mechanical Polishing).
- interlayer insulating film 203 is formed on gate electrode 230 and gate insulating film 200 so as to cover the exposed surface of gate electrode 230. Etching is performed so that openings are formed in the interlayer insulating film 203 and the gate insulating film 200. By this opening, each of n region 123 and contact region 124 is exposed on the upper surface of the mesa structure.
- source electrode 221 in contact with each of n region 123 and contact region 124 is formed on the upper surface of the mesa structure.
- a source wiring 222, a drain electrode 211, and a protective electrode 212 are formed. Thereby, the MOSFET 501 is obtained.
- the second insulating film 202 that constitutes the gate insulating film 200 together with the first insulating film 201 is formed on the first bottom 201B of the first insulating film 201.
- the first insulating film 201 is also provided on the first sidewall portion 201S.
- gate insulating film 200 has a greater thickness not only on bottom surface BT of trench TR but also on side wall surface SW that forms corner portion CR together with bottom surface BT in the vicinity of bottom surface BT. Therefore, the gate electrode capacitance can be further reduced as compared with the case where the gate insulating film 200 is thickened only on the bottom surface BT of the trench.
- the second side wall portion 202S of the second insulating film 202 is provided at a place where such a leakage current is most likely to flow. Thereby, a leak current can be suppressed.
- the channel surface CH (FIG. 3) is a special surface, the above temperature rise becomes remarkable due to the high mobility of the channel surface CH. Therefore, it is particularly important to suppress the leakage current.
- the impurity concentration of the p-type body layer 122 is often lowered as compared with the depth position DP (FIG. 5).
- the drain voltage is large, the short channel effect tends to occur.
- the influence of such a short channel effect can be reduced. It can also improve the short-circuit tolerance.
- the other end E2 of the second side wall portion 202S is located on the second region 201b away from the third region 201c. Accordingly, the second side wall 202S is further extended as compared with the case where the second side wall 202S is provided only on the first region 201a. Further, the second side wall portion 202S is provided apart from the boundary between the second region 201b and the third region 201c, which has a large influence on the channel characteristics. Therefore, the gate electrode capacitance can be more effectively reduced while suppressing the influence on the channel characteristics.
- the second semiconductor layer 122 preferably has a depth position DP (FIG. 5) where the impurity concentration reaches a peak, and the other end E2 of the second side wall 202S is preferably located deeper than the depth position DP. . Accordingly, the second side wall 202S is further extended as compared with the case where the second side wall 202S is provided only on the first region 201a. Further, the second side wall portion 202S is provided apart from the depth position DP that has a great influence on the channel characteristics. Therefore, it is possible to more effectively reduce the gate electrode capacitance while further suppressing the influence on the channel characteristics.
- the other end E2 of the second side wall portion 202S has an inclination angle AG of less than 70 degrees with respect to the first side wall portion 201S. Thereby, the change in the thickness of the gate insulating film 200 at the other end E2 is alleviated.
- first and second insulating films 201 and 202 have first and second carbon atom concentrations, respectively, and the second carbon atom concentration is smaller than the first carbon atom concentration. Accordingly, the second insulating film 202 has high dielectric breakdown resistance due to a low carbon atom concentration. Therefore, silicon carbide semiconductor device 501 has a large breakdown voltage. Since first insulating film 201 is formed by thermally oxidizing bottom surface BT and sidewall surface SW of trench TR made of silicon carbide, it contains a large amount of carbon derived from silicon carbide. On the other hand, the second insulating film 202 is formed by oxidizing the silicon film 302. Therefore, the carbon atom concentration of the second insulating film 202 is lower than the carbon atom concentration of the first insulating film 201.
- the first carbon atom concentration is preferably greater than 1 ⁇ 10 15 cm ⁇ 3 and the second carbon atom concentration is preferably less than 1 ⁇ 10 15 cm ⁇ 3 .
- the carbon atom concentration of the second insulating film 202 is sufficiently lowered. Therefore, the breakdown voltage of silicon carbide semiconductor device 501 can be further increased.
- the second insulating film 202 is preferably made of at least one of silicon oxide, silicon nitride, and phosphosilicate glass. Thereby, the breakdown voltage of silicon carbide semiconductor device 501 can be further increased.
- the second insulating film 202 is preferably a thermal oxide film that contains silicon and does not contain carbon. Thereby, the breakdown voltage of silicon carbide semiconductor device 501 can be further increased.
- the step of forming the second insulating film 202 by oxidizing the silicon film 302 is preferably performed at 800 ° C. or higher and 1150 ° C. or lower.
- oxidizing the silicon film 302 at 800 ° C. or higher surface roughness of the silicon film 302 can be suppressed.
- oxidizing the silicon film at 1150 ° C. or lower it is possible to suppress an increase in the vapor pressure of the second insulating film 202 made of silicon oxide formed by oxidizing the silicon film 302. As a result, the shape of the second insulating film 202 can be maintained.
- the step of forming the second insulating film 202 is a step of heating the second side wall portion 202S so that the angle AG of the other end E2 of the second side wall portion 202S with respect to the first side wall portion 201S becomes small. It is preferable to include. Thereby, the change in the thickness of the gate insulating film 200 at the other end E2 is alleviated.
- This step is preferably performed at 1300 ° C. or higher and 1400 ° C. or lower. Thereby, the angle AG of the other end E2 can be made sufficiently small without using an excessively high temperature.
- the second insulating film 202 may be formed by a deposition method, for example, a CVD method. May be formed directly.
- the “first conductivity type” is n-type and the “second conductivity type” is p-type, but these conductivity types may be interchanged. In this case, the donor and acceptor in the above description are also replaced.
- the “first conductivity type” is preferably n-type.
- the silicon carbide semiconductor device is not limited to a MOSFET, and may be, for example, a trench type IGBT (Insulated Gate Bipolar Transistor).
- the other end E2 of second side wall portion 202S of second insulating film 202 is connected to first region 201a and second region E2. It is located on the boundary of the region 201b.
- “located on the boundary” means that an error is allowed within a range in which each of the gate electrode capacitance and the channel characteristic is maintained at substantially the same level. Specifically, an error of about ⁇ 0.1 ⁇ m is allowed.
- the etch back process FOG.
- the second side wall portion 202S is extended to the maximum extent within a range that does not cover the second region 201b constituting the channel surface. Therefore, the gate electrode capacitance can be effectively reduced within a range that hardly affects the channel characteristics.
- the other end E2 of second side wall portion 202S of second insulating film 202 is separated from second region 201b and is second. 1 region 201a.
- the other end E2 is separated from the second region 201b by more than 0.1 ⁇ m.
- the etch back process (FIG. 13) in the first embodiment is further advanced, and the other end E2 of the second side wall portion 302S of the silicon film 302 is formed by What is necessary is just to position on the 1st area
- the second side wall 202S is extended within a range that does not approach the second region 201b constituting the channel surface. Therefore, the gate electrode capacitance can be reduced within a range that does not affect the channel characteristics.
- sidewall surface SW (FIG. 1) of trench TR preferably has a predetermined crystal plane (also referred to as a special plane), particularly on p-type body layer 122.
- a sidewall surface SW includes a surface S1 (first surface) having a surface orientation ⁇ 0-33-8 ⁇ as shown in FIG.
- the plane S1 preferably has a plane orientation (0-33-8).
- the side wall surface SW microscopically includes the surface S1, and the side wall surface SW further microscopically includes a surface S2 (second surface) having a surface orientation ⁇ 0-11-1 ⁇ .
- “microscopic” means that the dimensions are as detailed as at least a dimension of about twice the atomic spacing.
- TEM Transmission Electron Microscope
- the plane S2 preferably has a plane orientation (0-11-1).
- the surface S1 and the surface S2 of the sidewall surface SW constitute a composite surface SR having a surface orientation ⁇ 0-11-2 ⁇ . That is, the composite surface SR is configured by periodically repeating the surfaces S1 and S2. Such a periodic structure can be observed by, for example, TEM or AFM (Atomic Force Microscopy).
- the composite surface SR has an off angle of 62 ° macroscopically with respect to the ⁇ 000-1 ⁇ plane.
- “macroscopic” means ignoring a fine structure having a dimension on the order of atomic spacing. As such a macroscopic off-angle measurement, for example, a general method using X-ray diffraction can be used.
- composite surface SR has a plane orientation (0-11-2). In this case, the composite surface SR has an off angle of 62 ° macroscopically with respect to the (000-1) plane.
- the channel direction CD which is the direction in which carriers flow on the channel surface, is along the direction in which the above-described periodic repetition is performed.
- Si atoms are atoms of the A layer (solid line in the figure), B layer atoms (broken line in the figure) located below, C layer atoms (dotted line in the figure) located below, and B layer atoms (not shown) located below this It is provided repeatedly. That is, a periodic laminated structure such as ABCBABCBABCB... Is provided with four layers ABCB as one period.
- the atoms in each of the four layers ABCB constituting one cycle described above are (0-11-2) It is not arranged to be completely along the plane.
- the (0-11-2) plane is shown so as to pass through the position of the atoms in the B layer. You can see that it is shifted. For this reason, even if the macroscopic plane orientation of the surface of the silicon carbide single crystal, that is, the plane orientation when ignoring the atomic level structure is limited to (0-11-2), the surface is microscopic. Can take various structures.
- a surface S1 having a surface orientation (0-33-8) and a surface S2 connected to the surface S1 and having a surface orientation different from the surface orientation of the surface S1 are alternately provided. It is configured by being.
- the length of each of the surface S1 and the surface S2 is twice the atomic spacing of Si atoms (or C atoms).
- the surface obtained by averaging the surfaces S1 and S2 corresponds to the (0-11-2) surface (FIG. 23).
- the single crystal structure periodically includes a structure (part of the surface S1) equivalent to a cubic crystal when viewed partially.
- a surface S1 having a surface orientation (001) in a structure equivalent to the above-described cubic crystal and a surface S2 connected to the surface S1 and having a surface orientation different from the surface orientation of the surface S1 are alternated. It is comprised by being provided in.
- polytypes other than 4H may constitute the surface according to S2).
- the polytype may be 6H or 15R, for example.
- the horizontal axis indicates the angle D1 formed by the macroscopic surface orientation of the side wall surface SW having the channel surface and the (000-1) plane
- the vertical axis indicates the mobility MB.
- the plot group CM corresponds to the case where the side wall surface SW is finished as a special surface by thermal etching
- the plot group MC corresponds to the case where such thermal etching is not performed.
- the mobility MB in the plot group MC was maximized when the macroscopic surface orientation of the channel surface was (0-33-8). This is because, when thermal etching is not performed, that is, when the microscopic structure of the channel surface is not particularly controlled, the macroscopic plane orientation is set to (0-33-8). This is probably because the ratio of the formation of the visual plane orientation (0-33-8), that is, the plane orientation (0-33-8) considering the atomic level, stochastically increased.
- the mobility MB in the plot group CM was maximized when the macroscopic surface orientation of the channel surface was (0-11-2) (arrow EX).
- the reason for this is that, as shown in FIGS. 24 and 25, a large number of surfaces S1 having a plane orientation (0-33-8) are regularly and densely arranged via the surface S2, so that the surface of the channel surface is fine. This is probably because the proportion of the visual plane orientation (0-33-8) has increased.
- the mobility MB has an orientation dependency on the composite surface SR.
- the horizontal axis indicates the angle D2 between the channel direction and the ⁇ 0-11-2> direction
- the vertical axis indicates the mobility MB (arbitrary unit) of the channel surface.
- a broken line is added to make the graph easier to see.
- the angle D2 of the channel direction CD is preferably 0 ° or more and 60 ° or less, and more preferably substantially 0 °. all right.
- the sidewall surface SW may further include a surface S3 (third surface) in addition to the composite surface SR. More specifically, the sidewall surface SW may include a composite surface SQ configured by periodically repeating the surface S3 and the composite surface SR.
- the off angle of the side wall surface SW with respect to the ⁇ 000-1 ⁇ plane deviates from 62 ° which is the ideal off angle of the composite surface SR. This deviation is preferably small and preferably within a range of ⁇ 10 °.
- a surface included in such an angle range for example, there is a surface whose macroscopic plane orientation is a ⁇ 0-33-8 ⁇ plane.
- the off angle of the side wall surface SW with respect to the (000-1) plane deviates from 62 °, which is the ideal off angle of the composite surface SR.
- This deviation is preferably small and preferably within a range of ⁇ 10 °.
- a surface included in such an angle range for example, there is a surface whose macroscopic plane orientation is a (0-33-8) plane.
- Such a periodic structure can be observed by, for example, TEM or AFM.
- MOSFETs according to Examples and Comparative Examples were prepared.
- a MOSFET having the structure shown in FIG. 20 was prepared as a MOSFET according to the example.
- the gate insulating film 200 of the MOSFET according to the embodiment includes a first insulating film 201 and a second insulating film 202 provided on a part of the first insulating film 201.
- the MOSFET according to the embodiment has a structure in which the gate insulating film 200 facing the side wall surface SW of the trench TR is thickened.
- the other end E2 of the second sidewall portion 202S of the second insulating film 202 is located on the first region 201a away from the second region 201b.
- the distance from the bottom of the first insulating film 201 along the normal direction of the bottom surface BT of the trench TR to the other end E2 of the second sidewall 202S of the second insulating film 202 was 0.67 ⁇ m.
- the thickness of the second insulating film 202 was 200 nm.
- the angle AG (see FIG. 5) of the other end E2 of the second insulating film 202 was 67 ° at the channel portion, and was about 62 ° on the slope average.
- the first insulating film 201 and the second insulating film 202 are oxidized by oxidizing the first insulating film 301 and the silicon film 302 at 1100 ° C. for 95 minutes and then oxidizing at 1350 ° C.
- a gate insulating film 200 made of was formed. Thereafter, silicon carbide substrate 100 on which gate insulating film 200 including first insulating film 201 and second insulating film 202 was formed was heat-treated in a NO atmosphere at a temperature of 1350 ° C. for 28 minutes. Thereafter, silicon carbide substrate 100 on which gate insulating film 200 including first insulating film 201 and second insulating film 202 was formed was heat-treated in an Ar atmosphere at a temperature of 1350 ° C. for 40 minutes.
- the gate insulating film 200 of the MOSFET according to the comparative example is formed only from the first insulating film 201 and does not have the second insulating film 202.
- the MOSFET according to the comparative example has a structure in which the gate insulating film 200 facing the side wall surface SW of the trench TR is not thickened.
- the gate insulating film 200 was formed by oxidizing the silicon carbide substrate 100 at 1100 ° C. for 95 minutes and then oxidizing at 1350 ° C. for 6 minutes. Thereafter, silicon carbide substrate 100 on which gate insulating film 200 was formed was heat-treated in a NO atmosphere at a temperature of 1350 ° C. for 7 minutes. Thereafter, silicon carbide substrate 100 on which gate insulating film 200 was formed was heat-treated in an Ar atmosphere at a temperature of 1350 ° C. for 10 minutes.
- the capacitance C gd between the gate electrode 230 and the drain electrode 211 and the voltage V DS between the drain electrode 211 and the source electrode 221 will be described.
- the capacitance of the MOSFET according to the example is indicated by a solid line 101
- the capacitance of the MOSFET according to the comparative example is indicated by a broken line 102.
- the capacitance C gd of the MOSFET according to the example is the capacitance of the MOSFET according to the comparative example.
- the capacity was smaller than C gd .
- the capacitance C gd of the MOSFET according to the example when the voltage V DS between the drain electrode 211 and the source electrode 221 is 600 V is 32 pF, and the capacitance C gd of the MOSFET according to the comparative example is 27 pF.
- the gate electrode 230 is formed by increasing the thickness of the gate insulating film 200 facing the side wall surface SW of the trench TR (in other words, forming the second insulating film 202 on the first insulating film 201). It was confirmed that the capacitance C gd between the drain electrode 211 and the drain electrode 211 can be effectively reduced.
- 100 epitaxial substrate (silicon carbide substrate), 110 single crystal substrate, 121 n ⁇ layer (first semiconductor layer), 122 p-type body layer (second semiconductor layer), 123 n region (third semiconductor layer), 124 contact region, 200 gate insulating film, 201 first insulating film, 202 second insulating film, 201B first bottom, 201S first side wall, 201a to 201c first to third regions, 202B and 302B 2nd bottom part, 202S, 302S 2nd side wall part, 203 interlayer insulation film, 211 drain electrode, 212 protective electrode, 221 source electrode, 222 source wiring, 230 gate electrode, 302 silicon film, 401 mask, 402 resist layer, 501 to 503 MOSFET (silicon carbide semiconductor device), AG inclination angle, BT bottom surface, CH channel surface, CR corner portion, DP depth Position, E1 one end, E2 other end, SW side wall surface, SW1 to SW3 first to third side surfaces, TR trench.
- MOSFET silicon carbide
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Abstract
Description
第1の導電型を有する第1の半導体層と、第1の半導体層上に設けられ第2の導電型を有する第2の半導体層と、第2の半導体層上に設けられ第2の半導体層によって第1の半導体層と分離され第1の導電型を有する第3の半導体層とを含む炭化珪素基板が準備される。
(i) 炭化珪素半導体装置501~503は、炭化珪素基板100と、ゲート絶縁膜200と、ゲート電極230とを有する。炭化珪素基板100は、第1の導電型を有する第1の半導体層121と、第1の半導体層121上に設けられ第2の導電型を有する第2の半導体層122と、第2の半導体層122上に設けられ第2の半導体層122によって第1の半導体層121と分離され第1の導電型を有する第3の半導体層123とを含む。炭化珪素基板100にはトレンチTRが設けられている。トレンチTRは、第1の半導体層121からなる底面BTと、第1~第3の半導体層121~123のそれぞれからなる第1~第3の側面SW1~SW3を有する側壁面SWとを含む。ゲート絶縁膜200はトレンチTR上に設けられている。ゲート絶縁膜200は、側壁面SWおよび底面BTの各々を直接覆う第1の絶縁膜201と、第1の絶縁膜201上に設けられた第2の絶縁膜202とを有する。第1の絶縁膜201は、底面BT上に位置する第1の底部201Bと、側壁面SW上に位置する第1の側壁部201Sとを有する。第1の側壁部201Sは、第1~第3の側面SW1~SW3のそれぞれの上に位置する第1~第3の領域201a~201cを有する。第2の絶縁膜202は、第1の底部201B上に位置する第2の底部202Bと、第1の側壁部201S上に位置する第2の側壁部202Sとを有する。第2の側壁部202Sは、第2の底部202Bにつながった一方端E1と、第1および第2の領域201a,201bのいずれかの上に位置し第3の領域201cから離れた他方端E2とを有する。ゲート電極230はゲート絶縁膜200を介してトレンチTR上に設けられている。
(vii) 上記(i)~(vi)において、第1および第2の絶縁膜201,202のそれぞれは第1および第2の炭素原子濃度を有し、第2の炭素原子濃度は第1の炭素原子濃度よりも小さくてもよい。
(x) 上記(i)~(ix)において、第2の絶縁膜202は、シリコンを含み炭素を含まない膜の熱酸化膜であってもよい。
(xi) 炭化珪素半導体装置501~503の製造方法は、以下の工程を有する。
上記の製造方法によれば、第1の絶縁膜201とともにゲート絶縁膜200を構成する第2の絶縁膜202は、第1の絶縁膜201の第1の底部201B上だけでなく、第1の絶縁膜201の第1の側壁部201S上にも設けられる。これによりゲート絶縁膜200は、トレンチの底面BT上だけでなく、底面BT近傍で底面BTとともに角部CRを構成する側壁面SW面上でも、より大きな厚さを有する。よって、トレンチの底面BT上でのみゲート絶縁膜200が厚くされる場合に比して、ゲート電極容量をより小さくすることができる。
(xiv) 上記(xiii)において、第2の側壁部202Sを加熱する工程は1300℃以上1400℃以下で行なわれてもよい。
図1に示すように、本実施の形態の縦型MOSFET501(炭化珪素半導体装置)は、エピタキシャル基板100(炭化珪素基板)と、ゲート絶縁膜200と、ゲート電極230と、層間絶縁膜203と、ソース電極221と、ドレイン電極211と、ソース配線222と、保護電極212とを有する。
図6に示すように、単結晶基板110上にn-層121がエピタキシャル成長により形成される。このエピタキシャル成長は、たとえば原料ガスとしてシラン(SiH4)とプロパン(C3H8)との混合ガスを用い、キャリアガスとしてたとえば水素ガス(H2)を用いたCVD(Chemical Vapor Deposition)法により行うことができる。また、このときドナーとしてたとえば窒素(N)やリン(P)を導入することが好ましい。次に、n-層121上のp型ボディ層122と、p型ボディ層122上のn領域123とが形成される。具体的には、n-層121の上面にイオン注入が行われる。p型ボディ層122を形成するためのイオン注入においては、たとえばアルミニウム(Al)などのアクセプタがイオン注入される。またn領域123を形成するためのイオン注入においては、たとえばリン(P)などのドナーがイオン注入される。これにより、n-層121と、p型ボディ層122と、n領域123とを有するエピタキシャル基板100が形成される。なおイオン注入に代わり、不純物の添加をともなうにエピタキシャル成長が用いられてもよい。次に、イオン注入によってコンタクト領域124が形成される。次に、イオン注入により添加された不純物を活性化するための活性化熱処理が行われる。この熱処理の温度は、好ましくは1500℃以上1900℃以下であり、たとえば1700℃程度である。熱処理の時間は、たとえば30分程度である。熱処理の雰囲気は、好ましくは不活性ガス雰囲気であり、たとえばAr雰囲気である。以上のように炭化珪素基板100が準備される。
図19に示すように、本実施の形態のMOSFET502(炭化珪素半導体装置)においては、第2の絶縁膜202の第2の側壁部202Sの他方端E2は、第1の領域201aおよび第2の領域201bの境界上に位置している。ここでの「境界上に位置し」とは、ゲート電極容量およびチャネル特性の各々が実質的に同程度に保持される範囲内で、誤差を許容するものである。具体的には±0.1μm程度の誤差は許容される。このような第2の側壁部202Sを得るためには、たとえば、実施の形態1におけるエッチバック工程(図13)をより進行させ、シリコン膜302の第2の側壁部302Sの他方端E2を、上記境界の近傍に合わせればよい。なお上記以外の構成については、上述した実施の形態1の構成とほぼ同じであるため、同一または対応する要素について同一の符号を付し、その説明を繰り返さない。
図20に示すように、本実施の形態のMOSFET503(炭化珪素半導体装置)においては、第2の絶縁膜202の第2の側壁部202Sの他方端E2は、第2の領域201bから離れて第1の領域201a上に位置している。好ましくは、他方端E2は第2の領域201bから0.1μmよりも大きく離される。このような第2の側壁部202Sを得るためには、たとえば、実施の形態1におけるエッチバック工程(図13)をより進行させ、シリコン膜302の第2の側壁部302Sの他方端E2を、第2の領域201bから離して第1の領域201a上に位置させればよい。なお上記以外の構成については、上述した実施の形態1の構成とほぼ同じであるため、同一または対応する要素について同一の符号を付し、その説明を繰り返さない。
上述したように、トレンチTRの側壁面SW(図1)は好ましくは、特にp型ボディ層122上において、所定の結晶面(特殊面とも称する)を有する。このような側壁面SWは、図21に示すように、面方位{0-33-8}を有する面S1(第1の面)を含む。面S1は好ましくは面方位(0-33-8)を有する。
一般に、ポリタイプ4Hの炭化珪素単結晶を(000-1)面から見ると、図22に示すように、Si原子(またはC原子)は、A層の原子(図中の実線)と、この下に位置するB層の原子(図中の破線)と、この下に位置するC層の原子(図中の一点鎖線)と、この下に位置するB層の原子(図示せず)とが繰り返し設けられている。つまり4つの層ABCBを1周期としてABCBABCBABCB・・・のような周期的な積層構造が設けられている。
Claims (14)
- 炭化珪素半導体装置であって、
第1の導電型を有する第1の半導体層と、前記第1の半導体層上に設けられ第2の導電型を有する第2の半導体層と、前記第2の半導体層上に設けられ前記第2の半導体層によって前記第1の半導体層と分離され前記第1の導電型を有する第3の半導体層とを含む炭化珪素基板を備え、前記炭化珪素基板にはトレンチが設けられており、前記トレンチは、前記第1の半導体層からなる底面と、前記第1~第3の半導体層のそれぞれからなる第1~第3の側面を有する側壁面とを含み、前記炭化珪素半導体装置はさらに
前記トレンチ上に設けられたゲート絶縁膜を備え、前記ゲート絶縁膜は、前記側壁面および前記底面の各々を直接覆う第1の絶縁膜と、前記第1の絶縁膜上に設けられた第2の絶縁膜とを有し、前記第1の絶縁膜は、前記底面上に位置する第1の底部と、前記側壁面上に位置する第1の側壁部とを有し、前記第1の側壁部は前記第1~第3の側面のそれぞれの上に位置する第1~第3の領域を有し、前記第2の絶縁膜は、前記第1の底部上に位置する第2の底部と、前記第1の側壁部上に位置する第2の側壁部とを有し、前記第2の側壁部は、前記第2の底部につながった一方端と、前記第1および第2の領域のいずれかの上に位置し前記第3の領域から離れた他方端とを有し、前記炭化珪素半導体装置はさらに
前記ゲート絶縁膜を介して前記トレンチ上に設けられたゲート電極を備える、炭化珪素半導体装置。 - 前記第2の側壁部の前記他方端は、前記第1の領域および前記第2の領域の境界上に位置する、請求項1に記載の炭化珪素半導体装置。
- 前記第2の側壁部の前記他方端は、前記第2の領域から離れて前記第1の領域上に位置する、請求項1に記載の炭化珪素半導体装置。
- 前記第2の側壁部の前記他方端は、前記第3の領域から離れて前記第2の領域上に位置する、請求項1に記載の炭化珪素半導体装置。
- 前記第2の半導体層は不純物濃度がピークとなる深さ位置を有し、前記第2の側壁部の前記他方端は前記深さ位置よりも深くに位置する、請求項4に記載の炭化珪素半導体装置。
- 前記第2の側壁部の前記他方端は前記第1の側壁部に対して70度未満の傾斜角度を有する、請求項1~請求項5のいずれか1項に記載の炭化珪素半導体装置。
- 前記第1および第2の絶縁膜のそれぞれは第1および第2の炭素原子濃度を有し、前記第2の炭素原子濃度は前記第1の炭素原子濃度よりも小さい、請求項1~請求項6のいずれか1項に記載の炭化珪素半導体装置。
- 前記第1の炭素原子濃度は1×1015cm-3より大きく、前記第2の炭素原子濃度は1×1015cm-3より小さい、請求項7に記載の炭化珪素半導体装置。
- 前記第2の絶縁膜は、酸化珪素、窒化珪素、およびリン珪酸ガラスの少なくともいずれかから作られている、請求項1~請求項8のいずれか1項に記載の炭化珪素半導体装置。
- 前記第2の絶縁膜は、シリコンを含み炭素を含まない膜の熱酸化膜である、請求項1~請求項9のいずれか1項に記載の炭化珪素半導体装置。
- 第1の導電型を有する第1の半導体層と、前記第1の半導体層上に設けられ第2の導電型を有する第2の半導体層と、前記第2の半導体層上に設けられ前記第2の半導体層によって前記第1の半導体層と分離され前記第1の導電型を有する第3の半導体層とを含む炭化珪素基板を準備する工程と、
前記炭化珪素基板にトレンチを形成する工程とを備え、前記トレンチは、前記第1の半導体層からなる底面と、前記第1~第3の半導体層のそれぞれからなる第1~第3の側面を有する側壁面とを含み、さらに
前記側壁面および前記底面の各々を直接覆う第1の絶縁膜を形成する工程とを備え、前記第1の絶縁膜は、前記底面上に位置する第1の底部と、前記側壁面上に位置する第1の側壁部とを有し、前記第1の側壁部は、前記第1~第3の側面のそれぞれの上に位置する第1~第3の領域とを有し、さらに
前記第1の絶縁膜上にシリコン膜を形成する工程を備え、前記シリコン膜は、前記第1の底部上に位置する第2の底部と、前記第1の側壁部上に位置する第2の側壁部とを有し、前記第2の側壁部は、前記第2の底部につながった一方端と、前記第1および第2の領域のいずれかの上に位置し前記第3の領域から離れた他方端とを有し、さらに
前記シリコン膜を酸化することによって第2の絶縁膜を形成する工程を備え、前記第1および第2の絶縁膜はゲート絶縁膜を構成し、さらに
前記ゲート絶縁膜を介して前記トレンチ上にゲート電極を形成する工程を備える、炭化珪素半導体装置の製造方法。 - 前記シリコン膜を酸化することによって前記第2の絶縁膜を形成する工程は、800℃以上1150℃以下で行われる、請求項11に記載の炭化珪素半導体装置の製造方法。
- 前記第2の絶縁膜を形成する工程は、前記第1の側壁部に対する、前記第2の側壁部の前記他方端の角度が小さくなるように、前記第2の側壁部を加熱する工程を含む、請求項11に記載の炭化珪素半導体装置の製造方法。
- 前記第2の側壁部を加熱する工程は1300℃以上1400℃以下で行なわれる、請求項13に記載の炭化珪素半導体装置の製造方法。
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---|---|---|---|---|
JP2020077727A (ja) * | 2018-11-07 | 2020-05-21 | 三菱電機株式会社 | 半導体装置 |
JPWO2019142722A1 (ja) * | 2018-01-17 | 2021-01-07 | ローム株式会社 | 半導体装置およびその製造方法 |
WO2021024916A1 (ja) * | 2019-08-06 | 2021-02-11 | 住友電気工業株式会社 | 炭化珪素半導体装置 |
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JP6428900B1 (ja) * | 2017-11-29 | 2018-11-28 | 富士電機株式会社 | ダイオード素子およびダイオード素子の製造方法 |
JP2022144699A (ja) * | 2021-03-19 | 2022-10-03 | 富士電機株式会社 | 炭化珪素半導体装置および炭化珪素半導体装置の製造方法 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008109010A (ja) * | 2006-10-27 | 2008-05-08 | Toshiba Corp | 半導体装置及び半導体装置の製造方法 |
JP2009224365A (ja) * | 2008-03-13 | 2009-10-01 | Rohm Co Ltd | 半導体装置およびその製造方法 |
WO2012098861A1 (ja) * | 2011-01-17 | 2012-07-26 | パナソニック株式会社 | 半導体装置およびその製造方法 |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3471473B2 (ja) | 1994-04-06 | 2003-12-02 | 株式会社デンソー | 半導体装置及びその製造方法 |
DE69534888T2 (de) | 1994-04-06 | 2006-11-02 | Denso Corp., Kariya | Herstellungsverfahren für Halbleiterbauelement mit Graben |
JP2007201343A (ja) * | 2006-01-30 | 2007-08-09 | Central Res Inst Of Electric Power Ind | 炭化珪素半導体素子の製造方法 |
JP5283147B2 (ja) * | 2006-12-08 | 2013-09-04 | 国立大学法人東北大学 | 半導体装置および半導体装置の製造方法 |
JP5385567B2 (ja) * | 2007-09-03 | 2014-01-08 | ローム株式会社 | 半導体装置および半導体装置の製造方法 |
JP2010238738A (ja) * | 2009-03-30 | 2010-10-21 | Toshiba Corp | 半導体装置および半導体装置の製造方法 |
JP5246302B2 (ja) * | 2010-09-08 | 2013-07-24 | 株式会社デンソー | 半導体装置 |
JP5637916B2 (ja) * | 2011-03-31 | 2014-12-10 | トヨタ自動車株式会社 | 半導体装置及びその製造方法 |
JP5638558B2 (ja) * | 2012-03-26 | 2014-12-10 | 株式会社東芝 | 半導体装置及びその製造方法 |
JP5811973B2 (ja) * | 2012-09-12 | 2015-11-11 | 住友電気工業株式会社 | 炭化珪素半導体装置の製造方法 |
-
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Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008109010A (ja) * | 2006-10-27 | 2008-05-08 | Toshiba Corp | 半導体装置及び半導体装置の製造方法 |
JP2009224365A (ja) * | 2008-03-13 | 2009-10-01 | Rohm Co Ltd | 半導体装置およびその製造方法 |
WO2012098861A1 (ja) * | 2011-01-17 | 2012-07-26 | パナソニック株式会社 | 半導体装置およびその製造方法 |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPWO2019142722A1 (ja) * | 2018-01-17 | 2021-01-07 | ローム株式会社 | 半導体装置およびその製造方法 |
JP7241704B2 (ja) | 2018-01-17 | 2023-03-17 | ローム株式会社 | 半導体装置およびその製造方法 |
JP7512348B2 (ja) | 2018-01-17 | 2024-07-08 | ローム株式会社 | 半導体装置およびその製造方法 |
JP2020077727A (ja) * | 2018-11-07 | 2020-05-21 | 三菱電機株式会社 | 半導体装置 |
JP7061954B2 (ja) | 2018-11-07 | 2022-05-02 | 三菱電機株式会社 | 半導体装置 |
WO2021024916A1 (ja) * | 2019-08-06 | 2021-02-11 | 住友電気工業株式会社 | 炭化珪素半導体装置 |
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JP6443531B2 (ja) | 2018-12-26 |
JP2018088527A (ja) | 2018-06-07 |
DE112014001539T5 (de) | 2015-12-03 |
CN105074933A (zh) | 2015-11-18 |
JP6265122B2 (ja) | 2018-01-24 |
US9666681B2 (en) | 2017-05-30 |
CN105074933B (zh) | 2018-01-23 |
JPWO2014148130A1 (ja) | 2017-02-16 |
US20160005826A1 (en) | 2016-01-07 |
US9984879B2 (en) | 2018-05-29 |
US20170229305A1 (en) | 2017-08-10 |
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