JP5466815B2 - Semiconductor device - Google Patents

Description

The present invention relates to a nonvolatile semiconductor memory device which can be electrically written, read and erased, and a manufacturing method thereof. In particular, the present invention relates to a structure of a charge storage layer in the nonvolatile semiconductor memory device.

The market for non-volatile memories that can rewrite data electrically and store data even when the power is turned off is expanding. A nonvolatile memory has a structure similar to that of a MOSFET (Metal Oxide Field Effect Effect Transistor) and is characterized in that a region capable of accumulating charges for a long period is provided on a channel formation region. This charge storage region is formed on an insulating layer and is also called a floating gate because it is isolated from the surroundings. A control gate is further provided on the floating gate via an insulating layer.

In the so-called floating gate type nonvolatile memory having such a structure, an operation for accumulating and releasing electric charge in the floating gate is performed by a voltage applied to the control gate. In other words, data is stored by taking in and out charges held in the floating gate. Specifically, the injection and extraction of charges to and from the floating gate are performed by applying a high voltage between the semiconductor layer in which the channel formation region is formed and the control gate. At this time, it is said that Fowler-Nordheim type (FN type) tunnel current (NAND type) and thermal electrons (NOR type) flow through the insulating layer on the channel formation region. Thus, the insulating layer is also called a tunnel insulating layer.

Floating gate type non-volatile memories are required to have characteristics capable of retaining the charge stored in the floating gate for more than 10 years in order to guarantee reliability. For this reason, the tunnel insulating layer is required to have high insulating properties so as to prevent charges from leaking while being formed with a thickness through which a tunnel current flows.

The floating gate formed over the tunnel insulating layer is formed of silicon, which is the same semiconductor material as the semiconductor layer in which the channel formation region is formed. Specifically, a method of forming a floating gate with polycrystalline silicon is widespread, and for example, a method in which a polysilicon film is deposited to a thickness of 400 nm is known (see Patent Document 1).
JP 2000-58685 A (page 7, FIG. 7)

Since the floating gate of the nonvolatile memory element is formed of polycrystalline silicon, the energy level at the bottom of the conduction band of the semiconductor layer (channel formation region) formed of the same silicon material is the same. Rather, when the thickness of the polycrystalline silicon of the floating gate is reduced, the energy level at the bottom of the conduction band becomes higher than that of the semiconductor layer forming the channel formation region. When such a difference in energy level occurs, it becomes difficult for electrons to be injected from the semiconductor layer into the floating gate, and the write voltage becomes high. For this reason, in a nonvolatile memory in which the floating gate is formed of polycrystalline silicon, in order to lower the write voltage as much as possible, an n-type impurity such as phosphorus or arsenic is added to the floating gate to bring the Fermi level to the conduction band side. It is necessary to shift to.

With respect to the gate insulating layer provided between the floating gate and the semiconductor layer, the tunnel insulating layer can be thinned in order to write at a low voltage, while the floating gate charge is stably maintained for a long period of time. In order to prevent this, it is necessary to increase the thickness in order to prevent leakage of charges and intrusion of impurities.

Under such circumstances, a high write voltage is required to write information in the conventional nonvolatile memory. In addition, with respect to deterioration due to charge retention characteristics and repetitive rewriting, reliability is ensured by taking measures such as error detection and error correction by mounting redundant memory cells and devising a controller.

Therefore, an object of the present invention is to provide a nonvolatile semiconductor memory device that is excellent in writing characteristics and charge retention characteristics. It is another object of the present invention to provide a nonvolatile semiconductor memory device that can reduce a write voltage.

The present invention provides a semiconductor layer or semiconductor substrate having a channel formation region between a pair of impurity regions formed apart from each other, and an upper layer portion of the semiconductor layer or semiconductor substrate at a position substantially overlapping the channel formation region. The nonvolatile semiconductor memory device includes a first insulating layer, a charge storage layer, a second insulating layer, and a control gate. In the present invention, the charge storage layer is formed of an insulating layer capable of trapping charges.

As a material for forming the charge storage layer, germanium nitride, germanium oxide, germanium nitride to which oxygen is added, germanium oxide to which nitrogen is added, germanium nitride to which oxygen and hydrogen are added, germanium oxide to which nitrogen and hydrogen are added One or a plurality of germanium compounds such as can be selected.

Further, the charge accumulation layer can be formed of a layer in which particles are included in the layer formed of the germanium compound. The band gap of the particles contained in the charge storage layer is preferably smaller than the band gap of the semiconductor layer. For example, the band gap of the particles contained in the charge storage layer and the band gap of the semiconductor layer have a difference of 0.1 eV or more, and the former is preferably smaller.

As the particulate material contained in the charge storage layer, typically, germanium or a germanium compound is preferable. Examples of the germanium compound that forms the particles included in the charge storage layer include a silicon germanium alloy.

  The first insulating layer is preferably formed by solid phase oxidation or solid phase nitridation by plasma treatment on the surface of the semiconductor layer or the semiconductor substrate. The insulating layer formed by this method is dense, has a high withstand voltage, and is excellent in reliability. Therefore, the insulating layer can be formed thin and is a tunnel insulating layer for injecting charges into the charge storage layer. Suitable for the first insulating layer.

In the nonvolatile semiconductor memory device according to the present invention, the semiconductor layer is preferably formed on an insulating surface and separated into islands. At least a semiconductor layer forming a memory element and a semiconductor layer forming a logic circuit are preferably divided. That is, the present invention provides a semiconductor layer having a channel formation region between a pair of impurity regions formed apart from each other, and a first insulating layer at a position that is an upper layer portion of the semiconductor layer and substantially overlaps the channel formation region. And a non-volatile semiconductor memory device having a charge storage layer, a second insulating layer, and a control gate, in which a semiconductor layer is formed on an insulating surface.

When a charge storage layer is formed on a semiconductor region (semiconductor layer or semiconductor substrate) via a first insulating layer that functions as a tunnel insulating layer, a layer formed of an insulating germanium compound or an insulating property By using a layer in which particles containing germanium are dispersed in a layer formed of a germanium compound, the charge storage layer has a large number of sites (traps and dots) that hold charges, so that charges can be easily held. In addition, since the charge storage layer is insulative, it is possible to reduce leakage of charges held in the charge storage layer to the semiconductor layer even if the first insulating layer has a defect. As a result, charge retention in the charge storage layer can be improved and the thickness of the first insulating layer can be reduced, so that high-efficiency writing can be performed at a low voltage.

Further, by forming the charge storage layer using a material that matches the silicon system, a nonvolatile semiconductor memory device having excellent characteristics can be manufactured without impairing productivity. Since germanium is a material belonging to Group 14 of the same periodic table as silicon and is a semiconductor, it can finely process a thin film without imposing a burden on manufacturing equipment.

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Note that in the structures of the present invention described below, the same reference numerals may be used in common in different drawings.

FIG. 1 is a cross-sectional view for explaining a main configuration of a nonvolatile semiconductor memory device according to the present invention. FIG. 1A particularly shows a main part of a nonvolatile memory element. This nonvolatile memory element is manufactured using a substrate 10 having an insulating surface. As the substrate 10 having an insulating surface, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a metal substrate having an insulating layer formed on the surface, or the like can be used.

A semiconductor layer 14 is formed over the substrate 10 having the insulating surface. An insulating layer 12 that functions as a base film may be provided between the substrate 10 and the semiconductor layer 14. This insulating layer 12 prevents impurities such as alkali metals from diffusing from the substrate 10 to the semiconductor layer 14 and contaminates them, and may be appropriately provided as a blocking layer.

The insulating layer 12 is formed using an insulating material such as silicon oxide, silicon nitride, silicon containing oxygen and nitrogen (silicon oxynitride) by a CVD method, a sputtering method, or the like. For example, when the insulating layer 12 has a two-layer structure, a silicon oxynitride layer is formed as the first insulating layer, and the composition of the first silicon oxynitride layer is the same as that of the first insulating layer. Different silicon oxynitride layers may be formed. Alternatively, a silicon nitride layer may be formed as the first insulating layer, and a silicon oxide layer may be formed as the second insulating layer.

The semiconductor layer 14 is preferably a thin film formed of a single crystal semiconductor or a polycrystalline semiconductor. For example, after a semiconductor layer formed on the entire surface of the substrate 10 is crystallized on the substrate 10 by a sputtering method, a plasma CVD method, or a low pressure CVD method, a plurality of semiconductor layers 14 can be formed by selective etching. . That is, for the purpose of element isolation, it is preferable to form a plurality of island-shaped semiconductor layers on the insulating surface and to form one or more nonvolatile memory elements using the semiconductor layers. As the semiconductor material, silicon is preferable, and a silicon germanium semiconductor can also be used. As a method for crystallizing a semiconductor film, a laser crystallization method, a crystallization method using rapid thermal annealing (RTA) or a heat treatment using a furnace annealing furnace, a crystallization method using a metal element that promotes crystallization, or a combination of these methods. Can be used.

Thus, by separating and forming the semiconductor layer formed on the insulating surface in an island shape, even when the memory element array and the peripheral circuit are formed on the same substrate, the element can be effectively separated. That is, a memory element array that needs to be written and erased at a voltage of about 10V to 20V and a peripheral circuit that operates at a voltage of about 3V to 7V and mainly performs data input / output and command control on the same substrate. Even when formed, mutual interference due to a difference in voltage applied to each element can be prevented.

A p-type impurity may be implanted into the semiconductor layer 14. For example, boron is used as the p-type impurity, and may be added at a concentration of about 5 × 10 ¹⁵ atoms / cm ³ to 1 × 10 ¹⁶ atoms / cm ³ . This is for controlling the threshold voltage of the transistor, and acts effectively when added to the channel formation region. The channel formation region is formed in a region substantially overlapping with a gate 26 described later, and is located between a pair of impurity regions 18 of the semiconductor layer 14.

The pair of impurity regions 18 are regions functioning as a source region and a drain region in the nonvolatile memory element. The pair of impurity regions 18 is formed by adding phosphorus or arsenic which is an n-type impurity at a peak concentration of about 10 ²¹ atoms / cm ³ .

The first insulating layer 16, the charge storage layer 20, the second insulating layer 22, and the control gate electrode 24 are stacked on the semiconductor layer 14. In this specification, the charge storage layer 20 to the control gate are stacked. The stacked structure up to the electrode 24 may be called a gate 26.

The first insulating layer 16 can function as a tunnel insulating layer in the nonvolatile memory element. The second insulating layer 22 can function as a control insulating layer in the nonvolatile memory element. The first insulating layer 16 is formed of silicon oxide or a stacked structure of silicon oxide and silicon nitride. The first insulating layer 16 may be formed by depositing an insulating layer by a plasma CVD method or a low pressure CVD method, but is preferably formed by solid phase oxidation or solid phase nitridation by plasma treatment. This is because an insulating layer formed by oxidizing or nitriding a semiconductor layer (typically a silicon layer) by plasma treatment is dense, has high withstand voltage, and is excellent in reliability. Since the first insulating layer 16 is used as a tunnel insulating layer for injecting charges into the charge storage layer 20, it is possible to maintain insulation even if the thickness is reduced as it is strong. Therefore, it is preferable. The first insulating layer 16 is preferably formed to a thickness of 1 nm to 10 nm, preferably 1 nm to 5 nm. For example, when the gate length is 600 nm, the first insulating layer 16 can be formed to a thickness of 1 nm to 3 nm.

As solid-phase oxidation treatment or solid-phase nitridation treatment by plasma treatment, the electron density is 1 × 10 ¹¹ cm ⁻³ or more and 1 × 10 ¹³ cm ⁻³ or less when excited by microwaves (typically 2.45 GHz), and It is preferable to use plasma having an electron temperature of 0.5 eV to 1.5 eV. This is because in the solid phase oxidation treatment or solid phase nitridation treatment, a dense insulating layer is formed at a temperature of 500 ° C. or lower and a practical reaction rate is obtained.

When the surface of the semiconductor layer 14 is oxidized by this plasma treatment, oxygen (O ₂ ) or dinitrogen monoxide (N ₂ O) and a rare gas (He, Ne, Ar, Kr, Xe) are used in an oxygen atmosphere. Or in an atmosphere of oxygen or dinitrogen monoxide and hydrogen (H ₂ ) and a rare gas). In the case of performing nitridation by plasma treatment, nitrogen and hydrogen are used in a nitrogen atmosphere (for example, nitrogen (N ₂ ) and a rare gas (including at least one of He, Ne, Ar, Kr, and Xe) atmosphere). Plasma treatment is performed in a rare gas atmosphere or in a rare gas atmosphere with NH ₃ . As the rare gas, for example, Ar can be used. A gas in which Ar and Kr are mixed may be used.

FIG. 15 shows a configuration example of an apparatus for performing plasma processing. This plasma processing apparatus includes a support base 80 on which the substrate 10 is disposed, a gas supply unit 76 for introducing gas, an exhaust port 78 connected to a vacuum pump for exhausting gas, an antenna 72, a dielectric plate 74, a microwave supply unit 84 for supplying microwaves for plasma generation. In addition, the temperature of the substrate 10 can be controlled by providing the temperature control unit 82 on the support base 80.

Hereinafter, the plasma treatment will be described. Note that the plasma treatment includes oxidation treatment, nitridation treatment, oxynitridation treatment, hydrogenation treatment, and surface modification treatment for a semiconductor substrate, an insulating layer, and a conductive layer. For these processes, a gas supplied from the gas supply unit 76 may be selected according to the purpose.

The oxidation treatment or nitridation treatment may be performed as follows. First, the processing chamber is evacuated, and a plasma processing gas containing oxygen or nitrogen is introduced from the gas supply unit 76. The substrate 10 is heated to 100 ° C. to 550 ° C. by the room temperature or the temperature control unit 82. The interval between the substrate 10 and the dielectric plate 74 is about 20 nm to 80 mm (preferably 20 nm to 60 mm). Next, a microwave is supplied from the microwave supply unit 84 to the antenna 72. Then, plasma 86 is generated by introducing microwaves from the antenna 72 through the dielectric plate 74 into the processing chamber. When plasma excitation is performed by introduction of microwaves, plasma with a low electron temperature (3 eV or less, preferably 1.5 eV or less) and a high electron density (1 × 10 ¹¹ cm ⁻³ or more) can be generated. The surface of the semiconductor substrate can be oxidized or nitrided by oxygen radicals (which may include OH radicals) and / or nitrogen radicals (which may include NH radicals) generated by this high-density plasma. When a rare gas such as argon is mixed with the plasma processing gas, oxygen radicals or nitrogen radicals can be efficiently generated by the excited species of the rare gas. In this method, active radicals excited by plasma can be used effectively, whereby oxidation and nitridation by solid-phase reaction can be performed at a low temperature of 500 ° C. or lower.

In FIG. 1, an example of a suitable first insulating layer 16 formed by plasma treatment is to form a silicon oxide layer with a thickness of 3 nm to 6 nm on the surface of the semiconductor layer 14 by plasma treatment under an oxidizing atmosphere, and then A nitrogen plasma treatment layer is formed by treating the surface of the silicon oxide layer with a nitriding plasma in a nitrogen atmosphere. Specifically, first, a silicon oxide layer is formed with a thickness of 3 nm to 6 nm on the semiconductor layer 14 by plasma treatment in an oxygen atmosphere. Subsequently, a plasma treatment is performed in a nitrogen atmosphere to provide a nitrogen plasma treatment layer having a high nitrogen concentration at the interface between the silicon oxide layer and the charge storage layer or in the vicinity of the surface. Note that the vicinity of the surface means a depth of about 0.5 nm to 1.5 nm from the surface of the silicon oxide layer. For example, by performing plasma treatment in a nitrogen atmosphere, a structure containing nitrogen at a ratio of 20 to 50 atomic% at a depth of approximately 1 nm from the surface of the silicon oxide layer 16a is obtained.

By oxidizing the surface of a silicon layer as a typical example of the semiconductor layer 14 by plasma treatment, a dense oxide layer without distortion at the interface can be formed. Further, the oxide layer can be further densified by nitriding the oxide layer by plasma treatment to form a nitride layer by replacing oxygen in the surface layer portion with nitrogen. Accordingly, an insulating layer having a high withstand voltage can be formed, and the insulating layer can be formed thinner. Further, nitriding by plasma treatment has an advantage that hole conductivity is increased in the nonvolatile memory element and erasure is facilitated.

In any case, the heat formed at 950 ° C. to 1050 ° C. even when a glass substrate having a heat resistant temperature of 700 ° C. or less is used by using the solid phase oxidation treatment or solid phase nitridation treatment by the plasma treatment as described above. An insulating layer equivalent to the oxide film can be obtained. That is, a highly reliable tunnel insulating layer can be formed as the tunnel insulating layer of the nonvolatile memory element.

The charge storage layer 20 is formed on the first insulating layer 16. The charge storage layer 20 is preferably an insulating layer having a trap for holding charges. A typical example of such a material is a germanium compound. Examples of the germanium compound include germanium nitride, germanium oxide, germanium nitride to which oxygen is added, germanium oxide to which nitrogen is added, germanium nitride to which oxygen and hydrogen are added, germanium oxide to which nitrogen and hydrogen are added, and the like. Further, the charge storage layer 20 may contain germanium particles or silicon germanium particles.

The germanium particles and silicon germanium particles contained in the charge storage layer 20 have a charge storage layer 20 formed by the first insulating layer 16 against the barrier energy against electrons of the semiconductor layer 14 formed by the first insulating layer 16. The barrier energy for electrons increases. For this reason, it is possible to easily inject charges (electrons) from the semiconductor layer 14 to the charge storage layer 20, and to prevent the charge from disappearing from the charge storage layer 20.

The silicon germanium particles contained in the charge storage layer 20 preferably contain 10 atomic% or more of germanium with respect to silicon. This is because if the germanium concentration is 10 atomic% or more, the effect as a constituent element is reduced, and the band gap is not effectively reduced.

Germanium compounds such as germanium nitride, germanium oxide, germanium nitride to which oxygen is added, germanium oxide to which nitrogen is added, germanium nitride to which oxygen and hydrogen are added, germanium oxide to which nitrogen and hydrogen are added are used as a charge storage layer. When used, a charge storage layer is formed by performing a plasma CVD method in an atmosphere containing a germanium element (for example, an atmosphere containing GeH ₄ and N _2, GeH ₄ and NH _3, GeH ₄ and N ₂ O, or the like). Can do. In addition, a charge storage layer using germanium nitride can be formed by vapor-depositing a sintered body obtained by heating germanium oxide in an ammonia atmosphere. Further, germanium particles or silicon germanium particles can be formed by performing a plasma CVD method in an atmosphere containing GeH ₄ and H _2, GeH ₄ and SiH ₄ and H _{2, and the} like.

The second insulating layer 22 is formed of one or more layers such as silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide by a low pressure CVD method, a plasma CVD method, or the like. The thickness of the second insulating layer 22 is 1 nm to 20 nm, preferably 5 nm to 10 nm. For example, a silicon nitride layer 22a having a thickness of 3 nm and a silicon oxide layer 22b having a thickness of 5 nm can be used.

The control gate electrode 24 is a metal selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), chromium (Cr), niobium (Nb), or the like, or contains these metals as a main component. It is preferable to form with an alloy material or a compound material. Alternatively, polycrystalline silicon to which an impurity element such as phosphorus is added can be used. Further, the control gate electrode 24 may be formed by a laminated structure of one or more metal nitride layers 24a and the metal layer 24b. As the metal nitride, tungsten nitride, molybdenum nitride, or titanium nitride can be used. By providing the metal nitride layer 24a, the adhesion of the metal layer 24b can be improved and peeling can be prevented. Further, since the metal nitride such as tantalum nitride has a high work function, the thickness of the first insulating layer 16 can be increased by a synergistic effect with the second insulating layer 22.

In addition, as illustrated in FIG. 1B, the nonvolatile memory element may be manufactured using a semiconductor substrate 30. As the semiconductor substrate 30, a single crystal silicon substrate (silicon wafer) is preferably used. An SOI (Si-On-Insulator) substrate can also be used. As an SOI substrate, oxygen ions are implanted into a mirror-polished wafer and then annealed at a high temperature to form an oxide layer at a certain depth from the surface and so-called SIMOX made by eliminating defects generated in the surface layer. A (Separation by IMplanted Oxygen) substrate may be used.

When the semiconductor substrate 30 is n-type, a p-well 32 into which p-type impurities are implanted is formed. For example, boron is used as the p-type impurity, and is added at a concentration of about 5 × 10 ¹⁵ cm ⁻³ to 1 × 10 ¹⁶ cm ⁻³ . By forming the p-well 32, an n-channel transistor can be formed in this region. Further, the p-type impurity added to the p-well 32 also has an effect of controlling the threshold voltage of the transistor. A channel formation region to be formed in the semiconductor substrate 30 is formed in a region substantially coincident with a gate 26 described later, and is located between a pair of impurity regions 38 formed in the semiconductor substrate 30. .

The pair of impurity regions 38 functions as a source and a drain in the nonvolatile memory element. The pair of impurity regions 18 is formed by adding phosphorus or arsenic, which is an n-type impurity, at a peak concentration of about 10 ²¹ cm ⁻³ .

A spacer 28 is formed on the side wall of the gate 26, and has an effect of preventing leakage current (for example, current flowing between the charge storage layer 20 and the control gate electrode 24) at the end portion thereof. Further, the low concentration impurity regions 38 c can be formed at both ends of the gate 26 in the channel length direction by using the spacer 28. This low concentration impurity region 38c functions as a low concentration drain (LDD). Although the low-concentration impurity region 38c is not an essential structure, by providing this region, the electric field at the drain end can be relaxed and deterioration due to repeated writing and erasing can be suppressed.

On the semiconductor substrate 30, the first insulating layer 16, the charge storage layer 20, the second insulating layer 22, and the control gate electrode 24 are formed as in the nonvolatile memory element shown in FIG. Note that the first insulating layer 16 may be formed by oxidizing the surface of the semiconductor substrate 30 by thermal oxidation.

  In FIG. 1, the charge storage layer 20 and the control gate electrode 24 have the same width. However, in addition to this, the charge storage layer 20 is wider than the control gate electrode 24, The width of the layer 20 may be smaller than the width of the control gate electrode 24.

An operation mechanism of the nonvolatile memory element shown in FIG. 1 will be described with reference to a band diagram. In the band diagram shown below, the same elements as those in FIG. Here, a nonvolatile memory element having a thin semiconductor layer as shown in FIG. 1A will be described. However, a nonvolatile memory element using a single crystal semiconductor substrate as shown in FIG. It can also be applied to. Further, a layer containing germanium particles or silicon germanium particles is used as the charge storage layer 20 as follows. In the following description, germanium particles of the charge storage layer 20 are used.

FIG. 2 shows a state in which the semiconductor layer 14, the first insulating layer 16, the charge storage layer 20, the second insulating layer 22, and the control gate electrode 24 are stacked. FIG. 2 shows a case where no voltage is applied to the control gate electrode 24 and the Fermi level Ef of the semiconductor layer 14 and the Fermi level Efm of the control gate electrode 24 are equal.

The semiconductor layer 14 and the charge storage layer 20 are formed of different materials with the first insulating layer 16 interposed therebetween. The band gap Eg1 (energy difference between the lower end Ec of the conduction band and the upper end Ev of the valence band) of the semiconductor layer 14 and the band gap Eg2 of the charge storage layer 20 are different, and the latter band gap is combined to be small. . For example, silicon (1.12 eV) can be combined as the semiconductor layer 14, and germanium (0.72 eV) or silicon germanium (0.73 to 1.0 eV) can be combined as the charge storage layer 20. Germanium or silicon germanium may be hydrogenated. At this time, the hydrogen content relative to germanium or silicon germanium may be 1 to 30 atomic%. By forming the charge storage layer 20 with germanium containing hydrogen, recombination centers at the interface with the first insulating layer 16 can be reduced.

The first insulating layer 16 is represented by a silicon oxide layer 16a (about 8 eV) and a nitrogen plasma treatment layer 16b (about 5 eV) obtained by nitriding the silicon oxide by plasma treatment. The second insulating layer 22 also shows a state in which a silicon nitride layer 22a and a silicon oxide layer 22b are stacked from the charge storage layer 20 side.

The semiconductor layer 14 and the charge storage layer 20 are formed of different materials with the first insulating layer 16 interposed therebetween. In this case, the band gap of the semiconductor layer 14 and the band gap of the charge storage layer 20 are different, and the latter band gap is combined to be small. For example, the semiconductor layer 14 can be silicon (1.12 eV), and the charge storage layer 20 can be germanium (0.72 eV) or silicon germanium (0.73 to 1.1 eV). That is, the band gap Eg1 of silicon as the semiconductor layer 14 and the band gap Eg2 of germanium as the charge storage layer 20 satisfy the relationship of Eg1> Eg2. For each of the semiconductor layer 14 and the charge storage layer 20, the energy barrier against electrons by the first insulating layer 16, that is, the first barrier Be1 and the second barrier Be2 have different values, and a relationship of Be2> Be1 can be obtained. . In such a situation, an energy difference ΔE between the energy levels of the conduction band bottoms of the semiconductor layer 14 and the charge storage layer 20 occurs. As will be described later, this energy difference ΔE acts in the direction of accelerating the electrons when injecting the electrons from the semiconductor layer 14 into the charge storage layer 20 and contributes to lowering the write voltage.

By the way, in order to inject electrons into the charge storage layer 20, there are a method using thermal electrons and a method using FN tunnel current. When thermoelectrons are used, a positive voltage is applied to the control gate electrode 24, and a high voltage is applied to the drain to generate thermoelectrons. Thereby, thermoelectrons can be injected into the charge storage layer 20. When the FN type tunnel current is used, a positive voltage is applied to the control gate electrode 24 and injected from the semiconductor layer 14 into the charge storage layer 20 by the FN type tunnel current.

FIG. 47A shows the applied voltage when injecting into the charge storage layer 20 by the FN type tunnel current. FIG. 6A shows an example in which a nonvolatile memory element is formed using the semiconductor substrate 30 instead of the semiconductor layer 14 as shown in FIG. A positive high voltage (10V to 20V) is applied to the control gate electrode 24, and the source region 18a and the drain region 18b are set to 0V. The band diagram at this time is as shown in FIG. Electrons in the semiconductor layer 14 are injected into the first insulating layer 16 by the high electric field, and an FN tunnel current flows. As described with reference to FIG. 2, the relationship between the band gap Eg1 of the semiconductor layer 14 and the band gap Eg2 of the charge storage layer 20 is Eg1> Eg2. This difference acts as a self-bias so that electrons injected from the channel formation region of the semiconductor layer 14 are accelerated toward the charge storage layer 20. Thereby, the electron injection property can be improved.

The energy level at the bottom of the conduction band of the charge storage layer 20 is at a level lower by ΔE in terms of electronic energy than the energy level at the bottom of the conduction band of the semiconductor layer 14. Therefore, when electrons are injected into the charge storage layer 20, an internal electric field caused by this energy difference acts. This is realized by the combination of the semiconductor layer 14 and the charge storage layer 20 as described above. That is, it becomes easy to inject electrons from the semiconductor layer 14 into the charge storage layer 20, and the write characteristics in the nonvolatile memory element can be improved. This effect is the same when electrons are injected into the charge storage layer 20 using thermoelectrons.

  Note that when the charge storage layer 20 is formed only of a layer using a germanium compound, electrons injected from the semiconductor layer 14 are in the germanium compound layer at or near the interface between the first insulating layer 16 and the charge storage layer 20. Captured in a trap.

While electrons are held in the charge storage layer 20, the threshold voltage of the nonvolatile memory element shifts in the positive direction. This state can be a state in which data “0” is written. FIG. 4 shows a band diagram in the charge holding state. The electrons in the charge storage layer 20 are in a state of being confined in terms of energy by being sandwiched between the first insulating layer 16 and the second insulating layer 22. Although the potential is increased by carriers (electrons) stored in the charge storage layer 20, electrons are not emitted from the charge storage layer 20 unless energy exceeding the barrier energy is applied to the electrons. In this case, electrons are not emitted from the charge storage layer 20 unless energy exceeding the barrier energy is applied to the electrons. Further, the energy level at the bottom of the conduction band of the charge storage layer 20 is at a level lower by ΔE in terms of electronic energy than the energy level at the bottom of the conduction band of the semiconductor layer 14, and is an energy barrier against electrons. Is formed. This barrier can prevent electrons from flowing out into the semiconductor layer 14 due to the tunnel current. That is, the carriers accumulated in the charge accumulation layer 20 can be held even when left at a constant temperature of 150 ° C.

The data “0” is detected by detecting that the transistor does not turn on when a gate voltage is applied to turn on the nonvolatile memory element in a state where no charge is held in the charge storage layer 20. Is possible. Alternatively, as shown in FIG. 47B or FIG. 6B, when the bias is applied between the source region 18a and the drain region 18b and the control gate electrode 24 is set to 0 V, is the nonvolatile memory element conductive? It can be judged by no.

FIG. 48A shows a state in which charges are released from the charge storage layer 20 and data is erased from the nonvolatile memory element. In this case, a negative bias is applied to the control gate electrode 24 and an FN tunnel current is caused to flow between the semiconductor layer 14 and the charge storage layer 20. Alternatively, as shown in FIG. 48B, by applying a negative bias to the control gate electrode 24 and applying a positive high voltage to the source region 18a, an FN type tunnel current is generated, and the source region Electrons may be extracted to the 18a side.

  When forming a non-volatile memory element using a semiconductor substrate as shown in FIG. 1B instead of the semiconductor layer 14, the control gate electrode 24 is grounded as shown in FIG. This is performed by applying a negative bias to the p-well 32 and causing an FN tunnel current to flow between the channel formation region of the semiconductor substrate 30 and the charge storage layer 20. Alternatively, as shown in FIG. 7B, a negative bias is applied to the control gate electrode 24, and a positive high voltage is applied to the source region 38a, thereby generating an FN type tunnel current. The electrons may be extracted to the 38a side.

FIG. 5 shows a band diagram in this erased state. In the erase operation, since the first insulating layer 16 can be formed thin, electrons in the charge storage layer 20 can be emitted to the semiconductor layer 14 side by the FN tunnel current. Further, holes are more easily injected from the channel formation region of the semiconductor layer 14, and a substantial erasing operation can be performed by injecting the holes into the charge storage layer 20.

  When the charge storage layer 20 is formed only of a layer using a germanium compound, holes are injected from the semiconductor layer 14 into the first insulating layer 16 and are trapped in the trap of the charge storage layer 20. As a result, holes neutralize electrons trapped in the trap by writing, so that the threshold voltage can be shifted in the negative direction and erased.

By forming the charge storage layer 20 with an insulating germanium compound or a layer containing germanium particles in the germanium compound layer, the thickness of the first insulating layer 16 can be reduced. Thereby, it becomes easy to inject electrons into the charge storage layer 20 through the first insulating layer 16 by a tunnel current, and a low voltage operation is possible. Furthermore, it becomes possible to store electric charges at a low energy level, and a significant effect can be obtained that electric charges can be stored in a stable state.

In the nonvolatile memory element according to the present invention, as shown in FIGS. 2 and 3, a self-bias is generated between the semiconductor layer 14 and the charge storage layer 20 as Eg1> Eg2. This relationship is extremely important, and acts to facilitate injection when carriers are injected from the channel formation region of the semiconductor layer 14 into the charge storage layer 20. That is, the writing voltage can be lowered. On the contrary, it is difficult to release carriers from the charge storage layer 20. This acts to improve the storage retention characteristics of the nonvolatile memory element.

As described above, the nonvolatile memory element according to the present invention can easily inject charges from the semiconductor layer 14 into the charge storage layer 20 and can prevent the charge from being lost from the charge storage layer 20. . That is, when operating as a memory, high-efficiency writing can be performed at a low voltage, and charge retention characteristics can be improved.

Various nonvolatile semiconductor memory devices can be obtained using such a nonvolatile memory element. FIG. 8 shows an example of an equivalent circuit of a nonvolatile memory cell array. The memory cell MS01 that stores 1-bit information includes a selection transistor S01 and a nonvolatile memory element M01. The selection transistor S01 is inserted in series between the bit line BL0 and the nonvolatile memory element M01, and the gate is connected to the word line WL1. The gate of the nonvolatile memory element M01 is connected to the word line WL11. When writing data to the nonvolatile memory element M01, if the word line WL1 and the bit line BL0 are set to the H level, the BL1 is set to the L level, and a high voltage is applied to the word line WL11, the charge is stored in the charge storage layer 20 as described above. Accumulated. When erasing data, the word line WL1 and the bit line BL0 are set to H level, and a negative high voltage is applied to the word line WL11.

In this memory cell MS01, the select transistor S01 and the non-volatile memory element M01 are each formed of a semiconductor layer formed in an island shape on the insulating surface, so that other element isolation regions can be provided without special provision. Interference with the selection transistor or the nonvolatile memory element can be prevented. Further, since both the select transistor S01 and the nonvolatile memory element M01 in the memory cell MS01 are n-channel type, by forming both of them in a semiconductor layer separated into one island shape, a wiring for connecting the two elements is formed. Can be omitted.

FIG. 9 shows a NOR-type equivalent circuit in which a nonvolatile memory element is directly connected to a bit line. In this memory cell array, word lines WL and bit lines BL are arranged so as to intersect with each other, and nonvolatile memory elements are arranged at each intersection. In the NOR type, the drain of each nonvolatile memory element is connected to the bit line BL. The sources of the nonvolatile memory elements are commonly connected to the source line SL.

Also in this case, in the memory cell MS01, the nonvolatile memory element M01 is formed of a semiconductor layer formed on the insulating surface so as to be separated into islands, so that another nonvolatile memory can be obtained without providing an element isolation region. Interference with the element can be prevented. Further, a plurality of nonvolatile memory elements (for example, M01 to M23 shown in FIG. 9) are handled as one block, and these nonvolatile memory elements are formed by a semiconductor layer separated into one island shape, thereby making a block unit. The erase operation can be performed with.

The NOR type operation is, for example, as follows. In data writing, the source line SL is set to 0 V, a high voltage is applied to the word line WL selected for writing data, and a potential corresponding to data “0” and “1” is applied to the bit line BL. For example, H level and L level potentials are applied to the bit line BL for “0” and “1”, respectively. In order to write “0” data, in the nonvolatile memory element to which the H level is given, hot electrons are generated near the drain and injected into the charge storage layer. In the case of “1” data, such electron injection does not occur.

In a memory cell to which “0” data is given, hot electrons are generated in the vicinity of the drain due to a strong lateral electric field between the drain and the source, and this is injected into the charge storage layer. As a result, the state in which the threshold voltage is increased by the injection of electrons into the charge storage layer is “0”. In the case of “1” data, hot electrons are not generated, electrons are not injected into the charge storage layer, and a low threshold voltage state, that is, an erased state is maintained.

When erasing data, a positive voltage of about 10 V is applied to the source line SL, and the bit line BL is left floating. Then, a negative high voltage is applied to the word line WL (a negative high voltage is applied to the control gate), and electrons are extracted from the charge storage layer. As a result, the data “1” is erased.

For data reading, the source line SL is set to 0V and the bit line BL is set to about 0.8V, and the selected word line WL is set to an intermediate value between the threshold values of data “0” and “1”. A voltage is applied, and the presence / absence of current draw in the nonvolatile memory element is determined by a sense amplifier connected to the bit line BL.

FIG. 10 shows an equivalent circuit of the NAND memory cell array. A NAND cell NS1 in which a plurality of nonvolatile memory elements are connected in series is connected to the bit line BL. A plurality of NAND cells gather to constitute a block BLK1. The block BLK1 shown in FIG. 10 has 32 word lines (word lines WL0 to WL31). The nonvolatile memory elements located in the same row of the block BLK1 are commonly connected to word lines corresponding to this row.

In this case, since the select transistors S1 and S2 and the nonvolatile memory elements M0 to M31 are connected in series, they may be formed as a single semiconductor layer. Accordingly, wiring for connecting the nonvolatile memory elements can be omitted, so that integration can be achieved. Further, it is possible to easily separate the adjacent NAND cells. Further, the semiconductor layers of the select transistors S1 and S2 and the semiconductor layer of the NAND cell NS1 may be formed separately. When performing an erasing operation for extracting charges from the charge storage layers of the nonvolatile memory elements M0 to M31, the erasing operation can be performed in units of the NAND cells. Further, the nonvolatile memory elements (for example, the row of M30) commonly connected to one word line may be formed with one semiconductor layer.

The write operation is executed after the NAND cell NS1 is in the erased state, that is, the threshold value of each nonvolatile memory element of the NAND cell NS1 is in a negative voltage state. Writing is performed in order from the memory element M0 on the source line SL side. An example of writing to the memory element M0 is as follows.

In FIG. 11A, when "0" is written, for example, Vcc (power supply voltage) is applied to the selection gate line SG2 to turn on the selection transistor S2 and to set the bit line BL0 to 0 V (ground voltage). The selection gate line SG1 is set to 0V, and the selection transistor S1 is turned off. Next, the word line WL0 of the memory cell M0 is set to the high voltage Vpgm (about 20V), and the other word lines are set to the intermediate voltage Vpass (about 10V). Since the voltage of the bit line BL is 0V, the potential of the channel formation region of the selected memory cell M0 is 0V. Since the potential difference between the word line WL0 and the channel formation region is large, electrons are injected into the charge storage layer of the memory cell M0 by the FN tunnel current as described above. As a result, the threshold voltage of the memory cell M0 becomes positive (a state in which “0” is written).

On the other hand, when "1" is written, the bit line BL is set to Vcc (power supply voltage), for example, as shown in FIG. Since the voltage of the selection gate line SG2 is Vcc, the selection transistor S2 is cut off when Vcc minus Vth (Vcc−Vth) with respect to the threshold voltage Vth of the selection transistor S2. Accordingly, the channel formation region of the memory cell M0 is in a floating state. Next, when the high voltage Vpgm (20 V) is applied to the word line WL0 and the intermediate voltage Vpass (10 V) is applied to the other word lines, the capacitive coupling between each word line and the channel formation region causes the channel formation region. The voltage rises from Vcc-Vth and becomes about 8V, for example. Since the voltage of the channel formation region is boosted to a high voltage, the potential difference between the word line WL0 and the channel formation region is small unlike the case of writing “0”. Therefore, electron injection due to the FN tunnel current does not occur in the charge storage layer of the memory cell M0. Therefore, the threshold value of the memory cell M31 is maintained in a negative state (a state in which “1” is written).

When performing the erase operation, as shown in FIG. 49, a negative high voltage (Vers) is applied to all the word lines in the selected block. The bit line BL and the source line SL are brought into a floating state. Thereby, electrons in the charge storage layer are emitted to the semiconductor layer by the tunnel current in all the memory cells of the block. As a result, the threshold voltages of these memory cells shift in the negative direction.

  Further, when a nonvolatile memory element is formed using the semiconductor substrate 30 instead of the semiconductor layer 14, as shown in FIG. 12A, all word lines in the selected block are set to 0V, and p. A negative high voltage (Vers) is applied to the well. The bit line BL and the source line SL are in a floating state. Thereby, electrons in the charge storage layer are emitted to the semiconductor substrate by the tunnel current in all the memory cells of the block. As a result, the threshold voltages of these memory cells shift in the negative direction.

In the read operation shown in FIG. 12B, the voltage Vr (for example, 0 V) of the word line WL0 of the memory cell M0 selected to be read is used, and the word lines WL1 to WL31 and the select gate line SG1 of the non-selected memory cells are selected. SG2 is set to a read intermediate voltage Vread that is slightly higher than the power supply voltage. That is, as shown in FIG. 13, the memory elements other than the selected memory element function as transfer transistors. Thus, it is detected whether or not a current flows through the memory cell M0 selected for reading. That is, when the data stored in the memory cell M30 is “0”, the memory cell M0 is off, and the bit line BL is not discharged. On the other hand, in the case of “1”, since the memory cell M0 is turned on, the bit line BL is discharged.

FIG. 14 shows an example of a circuit block diagram of a nonvolatile semiconductor memory device. In the nonvolatile semiconductor memory device, the memory cell array 52 and the peripheral circuit 54 are formed on the same substrate. The memory cell array 52 has a configuration as shown in FIG. 8, FIG. 9, and FIG. The configuration of the peripheral circuit 54 is as follows.

A row decoder 62 for selecting a word line and a column decoder 64 for selecting a bit line are provided around the memory cell array 52. The address is sent to the control circuit 58 via the address buffer 56, and the internal row address signal and the internal column address signal are transferred to the row decoder 62 and the column decoder 64, respectively.

For writing and erasing data, a potential obtained by boosting the power supply potential is used. Therefore, a booster circuit 60 controlled by the control circuit 58 according to the operation mode is provided. The output of the booster circuit 60 is supplied to the word line WL and the bit line BL via the row decoder 62 and the column decoder 64. The sense amplifier 66 receives the data output from the column decoder 64. Data read by the sense amplifier 66 is held in the data buffer 68, and the data is randomly accessed under the control of the control circuit 58 and output via the data input / output buffer 70. The write data is temporarily held in the data buffer 68 via the data input / output buffer 70 and transferred to the column decoder 64 under the control of the control circuit 58.

Thus, in the nonvolatile semiconductor memory device, it is necessary to use a potential different from the power supply potential in the memory cell array 52. Therefore, it is desirable that at least the memory cell array 52 and the peripheral circuit 54 are electrically isolated from each other. In this case, as in Examples 1 to 3 to be described below, the non-volatile memory element and the peripheral circuit transistor are formed of a semiconductor layer formed on an insulating surface, whereby the insulation can be easily separated. Thus, a non-volatile semiconductor memory device with no malfunction and low power consumption can be obtained.

Hereinafter, the nonvolatile semiconductor memory device according to the present invention will be described in detail with reference to examples. In the structure of the present invention described below, reference numerals indicating the same elements are used in common in different drawings, and repetitive description in that case may be omitted.

  In this embodiment, an example of a nonvolatile semiconductor memory device will be described with reference to the drawings. Here, in the nonvolatile semiconductor memory device, an element such as a non-volatile memory element that constitutes a memory portion and a transistor that constitutes a logic portion that is provided on the same substrate as the memory portion and controls the memory portion. Are shown simultaneously.

  First, FIG. 8 shows a schematic diagram of a memory portion in a nonvolatile semiconductor memory device.

  The memory portion shown in this embodiment includes a plurality of memory cells each having a control transistor S and a nonvolatile memory element M. In FIG. 8, one memory cell is formed by the control transistor S01 and the nonvolatile memory element M01. Similarly, the control transistor S02 and the nonvolatile memory element M02, the control transistor S03 and the nonvolatile memory element M03, the control transistor S11 and the nonvolatile memory element M11, the control transistor S12 and the nonvolatile memory element M12, the control A memory cell is formed by the transistor S13 and the nonvolatile memory element M13.

  The gate electrode of the control transistor S01 is connected to the word line WL1, one of the source and the drain is connected to the bit line BL0, and the other is connected to the source or the drain of the nonvolatile memory element M01. The gate electrode of the nonvolatile memory element M01 is connected to the word line WL11, one of the source and the drain is connected to the source or the drain of the control transistor S01, and the other is connected to the source line SL0.

  Note that the control transistor provided in the memory portion has a higher driving voltage than the transistor provided in the logic portion. Therefore, the gate insulating film of the transistor provided in the memory portion and the transistor provided in the logic portion are formed with different thicknesses. It is preferable to do. For example, it is preferable to provide a thin film transistor with a thin gate insulating film when the driving voltage is small and it is desired to reduce the variation in threshold voltage. When the driving voltage is large and the gate insulating film is required to have a withstand voltage, the gate insulating film is It is preferable to provide a thick thin film transistor.

  Therefore, in this embodiment, an insulating layer having a small thickness is formed for a transistor in the logic portion where the driving voltage is small and the threshold voltage variation is desired to be small, and the withstand voltage of the gate insulating film is required to be large. A case where an insulating layer having a large thickness is formed for a transistor in a memory portion will be described below with reference to the drawings. 22 to 24 are top views, and FIGS. 21 to 19 are cross-sectional views taken along lines AB, CD, EF, and GH in FIGS. 22 to 24. . In addition, a thin film transistor provided in the logic portion is shown between AB and CD, a non-volatile memory element provided in the memory portion is shown between EF, and a thin film transistor provided in the memory portion is shown between GH. Show. Further, in this embodiment, the thin film transistor provided between A and B is p-channel type, the thin film transistor provided between C and D, the thin film transistor provided between GH and the n channel type, and the charge of the nonvolatile memory element provided between EF Although the case where accumulation is performed by electrons will be described, the nonvolatile semiconductor memory device of the present invention is not limited to this.

  First, island-shaped semiconductor layers 104, 106, 108, 110 are formed over the substrate 100 with the insulating layer 102 interposed therebetween, and the first insulating layer is formed so as to cover the island-shaped semiconductor layers 104, 106, 108, 110. 112 is formed (see FIGS. 16A and 22).

  The island-shaped semiconductor layers 104, 106, 108, and 110 are materials whose main component is silicon (Si) using a sputtering method, an LPCVD method, a plasma CVD method, or the like over the insulating layer 102 formed in advance on the substrate 100. And the like, and an amorphous semiconductor layer can be formed by crystallizing the amorphous semiconductor layer and then selectively etched. The crystallization of the amorphous semiconductor layer may be performed by laser crystallization, thermal crystallization using an RTA or furnace annealing furnace, thermal crystallization using a metal element that promotes crystallization, or a combination of these methods. Can be performed.

In the case where the semiconductor layer is crystallized or recrystallized by laser light irradiation, an LD-excited continuous wave (CW) laser (YVO ₄ , second harmonic (wavelength 532 nm)) is used as a laser light source. Can be used. The second harmonic is not particularly limited to the second harmonic, but the second harmonic is superior to higher harmonics in terms of energy efficiency. When the semiconductor layer is irradiated with the CW laser, energy is continuously given to the semiconductor layer. Therefore, once the semiconductor layer is in a molten state, the molten state can be continued. Furthermore, the solid-liquid interface of the semiconductor layer can be moved by scanning with a CW laser, and crystal grains that are long in one direction can be formed along the direction of this movement. The solid laser is used because the output stability is higher than that of a gas laser or the like, and stable processing is expected. Note that not only the CW laser but also a pulse laser having a repetition frequency of 10 MHz or more can be used. If a pulse laser with a high repetition frequency is used, the semiconductor layer can always remain in a molten state if the laser pulse interval is shorter than the time from when the semiconductor layer melts until it solidifies. A semiconductor layer including crystal grains that are long in one direction can be formed. Other CW lasers and pulse lasers with a repetition frequency of 10 MHz or more can also be used. For example, examples of the gas laser include an Ar laser, a Kr laser, and a CO ₂ laser. Examples of the solid-state laser include a YAG laser, a YLF laser, a YAlO ₃ laser, a GdVO ₄ laser, a KGW laser, a KYW laser, an alexandrite laser, a Ti: sapphire laser, a Y ₂ O ₃ laser, and a YVO ₄ laser. Further, there are ceramic lasers such as YAG laser, Y ₂ O ₃ laser, GdVO ₄ laser, and YVO ₄ laser. Examples of the metal vapor laser include a helium cadmium laser. In addition, it is preferable to emit laser light in TEM ₀₀ (single transverse mode) in a laser oscillator because energy uniformity of a linear beam spot obtained on the irradiated surface can be improved. In addition, a pulsed excimer laser may be used.

  The substrate 100 is selected from a semiconductor substrate such as a glass substrate, a quartz substrate, a ceramic substrate, a metal substrate (for example, a stainless steel substrate), and a Si substrate. In addition, a substrate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), or acrylic can be selected as the plastic substrate.

  The insulating layer 102 is formed using an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride by a CVD method, a sputtering method, or the like. For example, in the case where the insulating layer 102 has a two-layer structure, a silicon oxynitride layer is formed as the first insulating layer, and the composition is different from that of the first silicon oxynitride layer as the second insulating layer. A silicon oxynitride layer is preferably formed. Alternatively, a silicon nitride layer may be formed as the first insulating layer, and a silicon oxide layer may be formed as the second insulating layer. In this manner, by forming the insulating layer 102 functioning as a blocking layer, alkali metal such as Na or alkaline earth metal from the substrate 100 can be prevented from adversely affecting the element formed thereon. Note that the insulating layer 102 may be omitted when quartz is used for the substrate 100.

  The first insulating layer 112 is formed as a single layer or a stacked layer using an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride by a CVD method, a sputtering method, or the like. For example, when the first insulating layer 112 is provided as a single layer, the silicon oxynitride layer is formed with a thickness of 5 to 50 nm by a CVD method. In the case where the first insulating layer 112 is provided with a three-layer structure, a silicon oxynitride layer is formed as the first insulating layer, a silicon nitride layer is formed as the second insulating layer, A silicon oxynitride layer is formed as the insulating layer.

  Note that the first insulating layer 112 formed over the semiconductor layer 110 functions as a gate insulating film in a thin film transistor to be completed later.

  Next, the first insulating layer 112 formed over the semiconductor layers 104, 106, and 108 is selectively removed, so that the surfaces of the semiconductor layers 104, 106, and 108 are exposed. Here, the semiconductor layer 110 provided in the memory portion is selectively covered with a resist 114, and the first insulating layer 112 formed over the semiconductor layers 104, 106, and 108 is selectively removed by etching. (See FIG. 16B).

  Next, second insulating layers 116, 118, and 120 are formed over the semiconductor layers 104, 106, and 108, respectively (see FIG. 16C).

  The second insulating layers 116, 118, and 120 can be formed by performing heat treatment, plasma treatment, or the like on the semiconductor layers 104, 106, and 108. For example, an oxidation process, a nitridation process, or an oxynitride process is performed on the semiconductor layers 104, 106, and 108 by performing high-density plasma treatment on the semiconductor layers 104, 106, and 108, respectively. Second insulating layers 116, 118, and 120 are formed. Note that the second insulating layers 116, 118, and 120 may be formed by a CVD method or a sputtering method, or may be formed by performing high-density plasma treatment on a layer formed by a CVD method or a sputtering method. .

  For example, when a semiconductor layer containing Si as a main component is used as the semiconductor layers 104, 106, and 108 and is oxidized or nitrided by high-density plasma treatment, silicon oxide layers are used as the second insulating layers 116, 118, and 120. Alternatively, a silicon nitride layer is formed. Further, after the semiconductor layers 104, 106, and 108 are oxidized by high-density plasma treatment, nitriding treatment may be performed by performing high-density plasma treatment again. In this case, a silicon oxide layer is formed in contact with the semiconductor layers 104, 106, and 108, and a nitrogen plasma treatment layer is formed at the interface between the silicon oxide layer and the charge storage layer or at the silicon oxide layer at the interface.

  Here, the second insulating layers 116, 118, and 120 are formed with a thickness of 1 nm to 10 nm, preferably 1 nm to 5 nm. For example, an oxidation process is performed on the semiconductor layers 104, 106, and 108 by high-density plasma treatment to form a silicon oxide layer of approximately 3 nm on the surface of the semiconductor layers 104, 106, and 108, and then a nitridation process is performed by high-density plasma treatment. A nitrogen plasma treatment layer is formed on or near the surface of the silicon oxide layer. Specifically, first, the silicon oxide layer 16a is formed on the semiconductor layer 14 with a thickness of 3 nm to 6 nm by plasma treatment in an oxygen atmosphere. Then, a nitrogen plasma processing layer having a high nitrogen concentration is provided on or near the surface of the silicon oxide layer by subsequently performing plasma processing in a nitrogen atmosphere. Here, a plasma treatment is performed in a nitrogen atmosphere to form a structure in which nitrogen is contained at a ratio of 20 to 50 atomic% at a depth of approximately 1 nm from the surface of the silicon oxide layer. In the nitrogen plasma treatment layer, silicon (silicon oxynitride) containing oxygen and nitrogen is formed. At this time, it is preferable that the oxidation treatment and the nitriding treatment by the high-density plasma treatment are continuously performed without being exposed to the atmosphere. By continuously performing the high-density plasma treatment, it is possible to prevent contamination from entering and improve production efficiency. At this time, the surface of the first insulating layer 120 formed over the semiconductor layer 110 may also be oxidized or nitrided to form a silicon oxynitride layer.

Note that in the case where the semiconductor layer is oxidized by high-density plasma treatment, an atmosphere containing oxygen (for example, oxygen (O ₂ ) or dinitrogen monoxide (N ₂ O) and a rare gas (He, Ne, Ar, Kr And at least one of Xe), oxygen, or dinitrogen monoxide and hydrogen (H ₂ ) and a rare gas atmosphere. On the other hand, in the case of nitriding a semiconductor layer by high-density plasma treatment, an atmosphere containing nitrogen (for example, an atmosphere containing nitrogen (N ₂ ) and a rare gas (containing at least one of He, Ne, Ar, Kr, and Xe)) Under nitrogen, hydrogen, and rare gas atmosphere, or NH ₃ and rare gas atmosphere).

  As the rare gas, for example, Ar can be used. A gas in which Ar and Kr are mixed may be used. When the high-density plasma treatment is performed in a rare gas atmosphere, the first insulating layer 112 and the second insulating layers 116, 118, and 120 are formed of the rare gas (He, Ne, Ar, Kr, Xe) used for the plasma treatment. In the case where Ar is used, the first insulating layer 112 and the second insulating layers 116, 118, and 120 may contain Ar.

The high-density plasma treatment is performed in an atmosphere of the above gas at an electron density of 1 × 10 ¹¹ cm ⁻³ or more and an electron temperature of plasma of 1.5 eV or less. More specifically, the electron density is 1 × 10 ¹¹ cm ^{−3 to} 1 × 10 ¹³ cm ⁻³ and the plasma electron temperature is 0.5 eV to 1.5 eV. Since the electron density of the plasma is high and the electron temperature in the vicinity of the object to be processed (here, the semiconductor layers 104, 106, 108, and 110) formed on the substrate 100 is low, the object to be processed is damaged by the plasma. Can be prevented. Further, since the electron density of plasma is as high as 1 × 10 ¹¹ cm ⁻³ or higher, an oxide layer or a nitride layer formed by oxidizing or nitriding an irradiation object using plasma treatment is a CVD method. Compared with a layer formed by sputtering or the like, the thickness and the like are excellent in uniformity and a dense layer can be formed. In addition, since the electron temperature of plasma is as low as 1.5 eV or less, oxidation or nitridation can be performed at a lower temperature than conventional plasma treatment or thermal oxidation. For example, even if the plasma treatment is performed at a temperature that is 100 degrees or more lower than the strain point of the glass substrate, the oxidation or nitridation treatment can be sufficiently performed. As a frequency for forming plasma, a high frequency such as a microwave (eg, 2.45 GHz) can be used.

In this embodiment, when an object to be processed is oxidized by high-density plasma treatment, a mixed gas of oxygen (O ₂ ), hydrogen (H ₂ ), and argon (Ar) is introduced. The mixed gas used here may be introduced with 0.1 to 100 sccm of oxygen, 0.1 to 100 sccm of hydrogen, and 100 to 5000 sccm of argon. Note that the mixed gas is preferably introduced at a ratio of oxygen: hydrogen: argon = 1: 1: 100. For example, oxygen may be introduced at 5 sccm, hydrogen at 5 sccm, and argon at 500 sccm.

In addition, when performing nitriding treatment by high-density plasma treatment, a mixed gas of nitrogen (N ₂ ) and argon (Ar) is introduced. The mixed gas used here may be introduced at 20 to 2000 sccm of nitrogen and 100 to 10,000 sccm of argon. For example, nitrogen may be introduced at 200 sccm and argon at 1000 sccm.

  In this embodiment, the second insulating layer 120 formed over the semiconductor layer 108 provided in the memory portion functions as a tunnel oxide film in a nonvolatile memory element completed later. Therefore, the thinner the second insulating layer 120 is, the easier it is for the tunnel current to flow and the higher speed operation of the memory becomes possible. In addition, as the thickness of the second insulating layer 120 is thinner, charges can be stored in a charge storage layer to be formed later at a lower voltage, so that power consumption of the nonvolatile semiconductor memory device can be reduced. it can. Therefore, the second insulating layers 116, 118, and 120 are preferably formed thin (for example, 10 nm or less).

  In general, there is a thermal oxidation method as a method for forming a thin insulating layer over a semiconductor layer. However, when a substrate having a sufficiently low melting point such as a glass substrate is used as the substrate 100, the second method is performed by the thermal oxidation method. It is very difficult to form the insulating layers 116, 118, and 120. In addition, an insulating layer formed by a CVD method or a sputtering method includes defects inside the layer, so that the film quality is not sufficient, and there is a problem that defects such as pinholes occur when the thickness is formed thin. In addition, when the insulating layer is formed by a CVD method or a sputtering method, the end portion of the semiconductor layer is not sufficiently covered, and the conductive layer and the like that are formed later on the second insulating layer 120 and the semiconductor layer leak. There is a case. Therefore, as shown in this embodiment, by forming the second insulating layers 116, 118, and 120 by high-density plasma treatment, an insulating layer that is denser than an insulating layer formed by a CVD method, a sputtering method, or the like is formed. In addition, end portions of the semiconductor layers 104, 106, and 108 can be sufficiently covered with the second insulating layers 116, 118, and 120. As a result, high-speed operation and charge retention characteristics as a memory can be improved. Note that in the case where the second insulating layers 116, 118, and 120 are formed by a CVD method or a sputtering method, after the insulating layer is formed, high-density plasma treatment is performed, and the surface of the insulating layer is oxidized, nitrided, or oxidized. Nitriding is preferably performed.

  Next, the charge storage layer 122 is formed so as to cover the first insulating layer 112 and the second insulating layers 116, 118, and 120 (see FIG. 17A). The charge storage layer 122 can be formed using an insulating layer having defects that trap charges in the film, or an insulating layer containing conductive particles or semiconductor particles such as silicon. For example, as the charge storage layer 122, germanium nitride, germanium oxide, germanium nitride to which oxygen is added, germanium oxide to which nitrogen is added, germanium nitride to which oxygen and hydrogen are added, germanium oxide to which nitrogen and hydrogen are added, and the like The germanium compound can be used. Alternatively, germanium particles or silicon germanium particles may be included in the layer formed of these germanium compounds.

The charge storage layer 122 is formed of a germanium compound such as germanium nitride, germanium oxide, germanium nitride to which oxygen is added, germanium oxide to which nitrogen is added, germanium nitride to which oxygen and hydrogen are added, germanium oxide to which nitrogen and hydrogen are added. Is formed by performing plasma CVD in an atmosphere containing germanium (for example, an atmosphere containing GeH ₄ and N _2, GeH ₄ and NH _3, GeH ₄ and N ₂ O, or the like). Can be formed. Alternatively, the charge storage layer 122 using germanium nitride can be formed by vapor-depositing a sintered body obtained by heating germanium oxide in an ammonia atmosphere. The thickness of the charge storage layer 122 is 1 nm to 20 nm, preferably 1 nm to 10 nm.

Further, germanium particles or silicon germanium particles can be formed by performing a plasma CVD method in an atmosphere containing GeH ₄ and H _2, GeH ₄ and SiH ₄ and H _{2, and the} like. For example, germanium (GeH ₄ ) gas diluted with hydrogen to 5% to 10% is used, the heating temperature of the substrate 100 is set to 200 to 350 ° C., and high frequency power of 13.56 MHz to 60 MHz (for example, 27 MHz) is applied. Thus, germanium particles can be formed. The diameter of germanium particles or silicon germanium particles contained in the charge storage layer 122 is 0.1 nm or more and 10 nm or less, preferably 1 nm or more and 3 nm or less.

Here, germanium nitride having a thickness of 1 nm to 20 nm, preferably 1 nm to 10 nm, which is formed by a plasma CVD method using GeH ₄ and NH ₃ as raw materials, is used for the charge storage layer 122. Note that the charge storage layer 122 provided in the memory portion functions as a layer for trapping charges in a nonvolatile memory element to be completed later.

  Next, the second insulating layers 116 and 118 formed over the semiconductor layers 104 and 106, the charge storage layer 122, and the charge storage layer 122 formed over the semiconductor layer 110 are selectively removed, and the semiconductor layer 108 is formed. The second insulating layer 120 and the charge storage layer 122 formed in the step are left. Here, the semiconductor layer 108 provided in the memory portion is selectively covered with a resist 124 and selectively removed by etching the second insulating layers 116 and 118 and the charge storage layer 122 which are not covered with the resist 124. (See FIG. 17B). Note that FIG. 17B illustrates an example in which the charge storage layer 122 is formed by etching to selectively remove the charge storage layer 122 so that part of the charge storage layer 122 remains.

  Next, a third insulating layer 128 is formed so as to cover the semiconductor layers 104 and 106, the charge storage layer 126 formed above the semiconductor layer 108, and the first insulating layer 120 formed above the semiconductor layer 110. (See FIG. 17C).

  The third insulating layer 128 is formed as a single layer or a stacked layer using an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride by a CVD method, a sputtering method, or the like. For example, in the case where the third insulating layer 128 is provided as a single layer, the silicon oxynitride layer is formed with a thickness of 5 nm to 50 nm by a CVD method. In the case where the third insulating layer 128 is provided in a three-layer structure, a silicon oxynitride layer is formed as the first insulating layer, a silicon nitride layer is formed as the second insulating layer, A silicon oxynitride layer is formed as the insulating layer.

  Note that the third insulating layer 128 formed above the semiconductor layer 108 functions as a control insulating layer in a nonvolatile memory element to be completed later, and the third insulating layer formed above the semiconductor layers 104 and 106. 128 functions as a gate insulating film in a transistor to be completed later.

  Next, a conductive layer is formed so as to cover the third insulating layer 128 formed over the semiconductor layers 104, 106, 108, and 110 (see FIG. 18A). Here, an example is shown in which the conductive layer 130 and the conductive layer 132 are sequentially stacked as the conductive layer. Of course, the conductive layer may be formed of a single layer or a stacked structure of three or more layers.

  The conductive layers 130 and 132 are selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), and the like. Or an alloy material or a compound material containing these elements as main components. Alternatively, a metal nitride layer obtained by nitriding these elements can be used. In addition, a semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus can be used.

  Here, the conductive layer 130 is formed using tantalum nitride, and the conductive layer 132 is formed using tungsten over the stacked layer structure. In addition, as the conductive layer 130, a single layer or a stacked structure selected from tungsten nitride, molybdenum nitride, or titanium nitride is used, and as the conductive layer 132, a single layer or a stacked structure selected from tantalum, molybdenum, or titanium. Can be used.

  Next, the conductive layers 130 and 132 provided in a stacked manner are selectively etched and removed, so that the conductive layers 130 and 132 are left in portions above the semiconductor layers 104, 106, 108, and 110. Conductive layers 134, 136, 138, and 140 that function as gate electrodes are formed (see FIG. 18B). Note that the conductive layer 138 formed over the semiconductor layer 108 provided in the memory portion functions as a control gate in a nonvolatile memory element to be completed later. In addition, the conductive layers 134, 136, and 140 function as gate electrodes in a transistor that is completed later.

  Next, a resist 142 is selectively formed to cover the semiconductor layer 104, and an impurity element is introduced into the semiconductor layers 106, 108, and 110 using the resist 142 and the conductive layers 136, 138, and 140 as masks. (See FIG. 18C). As the impurity element, an impurity element imparting n-type conductivity or an impurity element imparting p-type conductivity is used. As the impurity element exhibiting n-type, phosphorus (P), arsenic (As), or the like can be used. As the p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, phosphorus (P) is used as the impurity element.

  In FIG. 18C, an impurity element 146 that forms a source region or a drain region and a channel formation region 144 are formed in the semiconductor layer 106 by introducing an impurity element. In the semiconductor layer 108, an impurity region 150 and a channel formation region 148 that form a source region or a drain region are formed. In the semiconductor layer 110, an impurity region 154 that forms a source region or a drain region and a channel formation region 152 are formed. Thereafter, the resist 142 is removed.

  Next, a resist 156 is selectively formed so as to cover the semiconductor layers 106, 108, and 110, and an impurity region is formed by introducing an impurity element into the semiconductor layer 104 using the resist 156 and the conductive layer 134 as a mask ( (See FIG. 19A and FIG. 23). As the impurity element, an impurity element imparting n-type conductivity or an impurity element imparting p-type conductivity is used. As the impurity element exhibiting n-type, phosphorus (P), arsenic (As), or the like can be used. As the p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, an impurity element (eg, boron (B)) having a conductivity type different from that of the impurity element introduced into the semiconductor layers 106, 108, and 110 in FIG. 18C is introduced. As a result, an impurity region 160 for forming a source region or a drain region and a channel formation region 158 are formed in the semiconductor layer 104. Thereafter, the resist 156 is removed.

  Next, an insulating layer 162 was formed so as to cover the third insulating layer 128 and the conductive layers 134, 136, 138, and 140, and the semiconductor layers 104, 106, 108, and 110 were formed over the insulating layer 162, respectively. A conductive layer 164 electrically connected to the impurity regions 146, 150, 154, and 160 is formed (see FIGS. 19B and 24).

  The insulating layer 162 is formed by CVD, sputtering, or the like using an oxygen or nitrogen insulating layer such as silicon oxide, silicon nitride, or silicon oxynitride, or a layer containing carbon such as DLC (diamond-like carbon), epoxy, polyimide, or polyamide. , Polyvinylphenol, benzocyclobutene, an organic material such as acrylic, or a single layer or a laminated structure made of a siloxane material such as a siloxane resin. Note that the siloxane material corresponds to a material including a Si—O—Si bond. Siloxane has a skeleton structure formed of a bond of silicon (Si) and oxygen (O). As a substituent, an organic group containing at least hydrogen (for example, an alkyl group or an aromatic hydrocarbon group) is used. A fluoro group can also be used as a substituent. Alternatively, an organic group containing at least hydrogen and a fluoro group may be used as a substituent.

  The conductive layer 164 is formed by a CVD method, a sputtering method, or the like by aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper ( Cu), gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), silicon (Si), or an alloy material containing these elements as a main component or The compound material is formed as a single layer or a stacked layer. The alloy material containing aluminum as a main component corresponds to, for example, a material containing aluminum as a main component and containing nickel, or an alloy material containing aluminum as a main component and containing nickel and one or both of carbon and silicon. The conductive layer 164 has, for example, a stacked structure of a barrier layer, an aluminum silicon (Al—Si) layer, and a barrier layer, or a stacked structure of a barrier layer, an aluminum silicon (Al—Si) layer, a titanium nitride (TiN) layer, and a barrier layer. Adopt it. Note that the barrier layer corresponds to a thin film formed of titanium, a nitride of titanium, molybdenum, or a nitride of molybdenum. Aluminum and aluminum silicon are optimal materials for forming the conductive layer 164 because they have low resistance and are inexpensive. In addition, when an upper layer and a lower barrier layer are provided, generation of hillocks of aluminum or aluminum silicon can be prevented. In addition, when a barrier layer made of titanium, which is a highly reducing element, is formed, even if a thin natural oxide film is formed on the crystalline semiconductor layer, the natural oxide film is reduced, and the crystalline semiconductor layer is excellent. Contact can be made.

  In this embodiment, an example in which an insulating layer functioning as a control insulating film of a nonvolatile memory element formed in a memory portion and a gate insulating film of a thin film transistor formed in a logic portion are formed at the same time (FIG. 17C). However, the present invention is not limited to this. For example, it may be formed as shown in FIG. This will be specifically described below.

  First, after forming similarly to FIG. 17A, a third insulating layer 128 is formed over the charge storage layer 122 (FIG. 20A). Next, after selectively forming a resist 124 so as to cover the semiconductor layer 108, the charge storage layer 122 and the third insulating layer 128 formed over the semiconductor layers 104, 106, and 110 are selectively removed. (FIG. 20B). After that, insulating layers 168 and 170 functioning as gate insulating films are formed on the exposed surfaces of the semiconductor layers 104 and 106 (FIG. 20C). The insulating layers 168 and 170 may be provided using high-density plasma treatment as described in the formation of the second insulating layers 116, 118, and 120, or can be formed by a CVD method or a sputtering method.

  By forming as shown in FIG. 20, the gate insulating film of the thin film transistor formed in the logic portion and the control insulating film of the nonvolatile memory element formed in the memory portion can be provided with different thicknesses and materials.

  In the process shown in this embodiment, an insulating layer 172 (also referred to as a sidewall) may be provided so as to be in contact with the side surfaces of the conductive layers 134, 136, 138, and 140 that function as gate electrodes (see FIG. 21). . By introducing an impurity element into the semiconductor layers 104, 106, 108, and 110 using the insulating layer 172 as a mask, low-concentration impurity regions 180, 174, 176, which function as LDDs, respectively, are added to the semiconductor layers 104, 106, 108, and 110, respectively. 178 can be formed.

  Note that the insulating layer 172 may be provided so as to be in direct contact with the semiconductor layer 104 (see FIG. 21A), or another insulating layer or a charge storage layer is provided below the insulating layer 172. It is also possible (see FIG. 21B).

  In this embodiment, the structure in which the charge storage layer 126 is provided on the entire upper surface of the semiconductor layer 108 provided in the memory portion is shown, but the present invention is not limited to this. For example, a structure in which the charge storage layer 126 is selectively provided at a portion where the semiconductor layer 108 and the conductive layer 138 intersect (see FIG. 46) may be employed. Note that in the nonvolatile memory element, when the channel length is L and the channel width is W, the charge storage layer 126 may be provided so as to be larger than the channel length L and the channel width W (see FIG. 46). It may be provided so as to be larger than one of the length L and the channel width W, or may be provided so as to be smaller than the channel length L and the channel width W (provided on the semiconductor layer 108).

  This example can be implemented in combination with any of the other embodiments or examples shown in this specification.

  In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device, which is different from the above embodiment, will be described with reference to drawings. In addition, when referring to the same thing as the said Example, it shows using the same code | symbol and abbreviate | omits description. 25 to 27, the thin film transistors provided in the logic portion are shown between AB and CD, the non-volatile memory elements provided in the memory portion are shown between EF, and between GH are shown. A thin film transistor provided in a memory portion is shown.

  First, as shown in the above embodiment, after forming in the same manner up to FIG. 16A, a resist 114 is selectively formed so as to cover the end portions of the semiconductor layers 104, 106, and 108 and the semiconductor layer 110, The first insulating layer 112 which is not covered with the resist 114 is selectively removed (see FIG. 25A). In other words, here, the semiconductor layer 110 and the semiconductor layers 104, 106, and 108 are covered with the first insulating layer 112.

  This is because when the first insulating layer 112 formed on the semiconductor layers 104, 106, and 108 is all removed by etching, the insulating layer is formed at the end portions of the semiconductor layers 104, 106, and 108 and the insulating layer 102. It is provided in order to prevent the formation of a recess (counterbore) in 102. In the case where a recess is formed in the insulating layer 102, a problem such as poor coverage occurs when an insulating layer or the like that covers the semiconductor layers 104, 106, and 108 is formed thereafter. Thus, the semiconductor layers 104, 106, and 108 are thus formed. It is effective to cover the end of the first insulating layer 112 with the first insulating layer 112. Thereafter, the resist 114 is removed.

  Next, second insulating layers 116, 118, and 120 are formed over the semiconductor layers 104, 106, and 108, respectively (see FIG. 25B). The second insulating layers 116, 118, and 120 can be formed by any of the methods described in the above embodiments. Here, a silicon oxide layer is formed as the second insulating layers 116, 118, and 120 by continuously performing oxidation treatment and nitridation treatment using high-density plasma treatment, and then is formed on or near the surface of the silicon oxide layer. A nitrogen plasma treatment layer having a high nitrogen concentration is formed.

  Next, the charge storage layer 122 is formed so as to cover the first insulating layer 112 and the second insulating layers 116, 118, and 120 formed above the semiconductor layer 110 (see FIG. 25C). The charge storage layer 122 can be formed of any of the materials described in the above embodiments. Here, a germanium nitride layer containing germanium particles is formed.

  Next, the second insulating layers 116 and 118 and the charge storage layer 122 formed over the semiconductor layers 104 and 106 are selectively removed, and the second insulating layer 120 and the charge storage formed over the semiconductor layer 108 are removed. The layer 122 and the charge storage layer 122 formed above the semiconductor layer 110 are left. Here, the semiconductor layer 108 and the semiconductor layer 110 provided in the memory portion are selectively covered with a resist 124, and the second insulating layers 116 and 118 and the charge storage layer 122 that are not covered with the resist 124 are etched. This is selectively removed (see FIG. 26A). Note that FIG. 26A illustrates an example in which the charge storage layer 122 is formed by etching to selectively remove the charge storage layer 122 so that part of the charge storage layer 122 remains. Note that as shown in the above embodiment, the charge storage layer 122 formed above the semiconductor layer 110 may be removed. Thereafter, the resist 124 is removed.

  Next, a third insulating layer 128 is formed so as to cover the charge accumulation layer 126 formed over the semiconductor layers 104 and 106 and the semiconductor layers 108 and 110 (see FIG. 26B).

  The third insulating layer 128 is formed using any of the materials described in the above embodiments. For example, as the third insulating layer 128, a silicon oxynitride layer is formed with a thickness of 5 nm to 50 nm by a CVD method.

  Note that the third insulating layer 128 formed above the semiconductor layer 108 functions as a control insulating layer in a nonvolatile memory element to be completed later, and the third insulating layer formed above the semiconductor layers 104 and 106. 128 functions as a gate insulating film in a transistor to be completed later.

  Next, conductive layers 134, 136, 138, and 140 that function as gate electrodes are formed over the semiconductor layers 104, 106, 108, and 110, respectively (see FIG. 26C). Note that the conductive layer 138 formed over the semiconductor layer 108 provided in the memory portion functions as a control gate in a nonvolatile memory element to be completed later. In addition, the conductive layers 134, 136, and 140 function as gate electrodes in a transistor that is completed later.

  Next, a resist 142 is selectively formed to cover the semiconductor layer 104, and an impurity element is introduced into the semiconductor layers 106, 108, and 110 using the resist 142 and the conductive layers 136, 138, and 140 as masks. (See FIG. 27A). As the impurity element, an impurity element imparting n-type conductivity or an impurity element imparting p-type conductivity is used. As the impurity element exhibiting n-type, phosphorus (P), arsenic (As), or the like can be used. As the p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, phosphorus (P) is used as the impurity element. Thereafter, the resist 142 is removed.

  In FIG. 27A, an impurity element 146 that forms a source region or a drain region and a channel formation region 144 are formed in the semiconductor layer 106 by introducing an impurity element. In the semiconductor layer 108, an impurity region 150 and a channel formation region 148 that form a source region or a drain region are formed. In the semiconductor layer 110, an impurity region 154 that forms a source region or a drain region and a channel formation region 152 are formed.

  Next, a resist 156 is selectively formed so as to cover the semiconductor layers 106, 108, and 110, and an impurity region is formed by introducing an impurity element into the semiconductor layer 104 using the resist 156 and the conductive layer 134 as a mask ( FIG. 27 (B)). As the impurity element, an impurity element imparting n-type conductivity or an impurity element imparting p-type conductivity is used. As the impurity element exhibiting n-type, phosphorus (P), arsenic (As), or the like can be used. As the p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, an impurity element (eg, boron (B)) having a conductivity type different from that of the impurity element introduced into the semiconductor layers 106, 108, and 110 in FIG. 27A is introduced. As a result, an impurity region 160 for forming a source region or a drain region and a channel formation region 158 are formed in the semiconductor layer 104. Thereafter, the resist 156 is removed.

  Next, an insulating layer 162 was formed so as to cover the third insulating layer 128 and the conductive layers 134, 136, 138, and 140, and the semiconductor layers 104, 106, 108, and 110 were formed over the insulating layer 162, respectively. A conductive layer 164 electrically connected to the impurity regions 160, 150, 154, and 146 is formed (see FIG. 27C).

  The insulating layer 162 and the conductive layer 164 can be formed using any of the materials described in the above embodiments.

  Note that this example can be implemented in combination with any of the other embodiments and examples shown in this specification.

  In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device, which is different from the above embodiment, will be described with reference to drawings. In addition, when referring to the same thing as the said Example, it shows using the same code | symbol and abbreviate | omits description. 28 to 30, thin film transistors provided in the logic portion are shown between AB and CD, non-volatile memory elements provided in the memory portion are shown between EF, and between GH are shown. A thin film transistor provided in a memory portion is shown.

  First, the semiconductor layer 103 is formed over the substrate 100 with the insulating layer 102 interposed therebetween, and the first insulating layer 112 is formed over the semiconductor layer 103 (see FIG. 28A).

  The semiconductor layer 103 is an amorphous semiconductor layer formed using a material having silicon (Si) as a main component by using a sputtering method, an LPCVD method, a plasma CVD method, or the like over an insulating layer 102 formed in advance on the substrate 100. And the amorphous semiconductor layer can be crystallized. The crystallization of the amorphous semiconductor layer may be performed by laser crystallization, thermal crystallization using an RTA or furnace annealing furnace, thermal crystallization using a metal element that promotes crystallization, or a combination of these methods. Can be performed.

  Next, a resist 114 is selectively provided over the first insulating layer 112, and etching is performed using the resist 114 as a mask, so that the first insulating layer 112 is left and the second insulating layer 113 is formed. (See FIG. 28B).

  Next, a second insulating layer 115 is formed over the exposed semiconductor layer 103 (see FIG. 28C).

  The second insulating layer 115 can be formed by performing heat treatment, plasma treatment, or the like on the exposed semiconductor layer 103. For example, by performing oxidation treatment, nitridation treatment, or oxynitridation treatment on the semiconductor layer 103 by high-density plasma treatment, a silicon oxide layer having a nitrogen plasma treatment layer on or near the surface is formed on each semiconductor layer 103. The second insulating layer 115 is formed. Note that the second insulating layer 115 may be formed by a CVD method or a sputtering method, or may be formed by performing high-density plasma treatment on a layer formed by a CVD method or a sputtering method.

  For example, in the case where a semiconductor layer containing Si as a main component is used as the semiconductor layer 103 and oxidized or nitrided by high-density plasma treatment, a silicon oxide layer or a silicon nitride layer is formed as the second insulating layer 115. . Alternatively, after the semiconductor layer 103 is oxidized by high-density plasma treatment, nitriding treatment may be performed by performing high-density plasma treatment again. In this case, a silicon oxide layer is formed in contact with the semiconductor layer 103, and a nitrogen plasma treatment layer is formed on or near the surface of the silicon oxide layer.

  Here, the second insulating layer 115 is formed with a thickness of 1 nm to 10 nm, preferably 1 nm to 5 nm. For example, after oxidizing the semiconductor layer 103 by high-density plasma treatment and forming a silicon oxide layer on the surface of the semiconductor layer 103, nitriding treatment is performed by high-density plasma treatment and nitrogen plasma is formed on or near the surface of the silicon oxide layer. A treatment layer is formed. At this time, it is preferable that the oxidation treatment and the nitriding treatment by the high-density plasma treatment are continuously performed without being exposed to the atmosphere. By continuously performing the high-density plasma treatment, it is possible to prevent contamination from entering and improve production efficiency. At this time, the surface of the first insulating layer 113 may also be oxidized or nitrided to form a silicon oxynitride layer.

  Next, the charge accumulation layer 122 is formed over the second insulating layer 115 and the first insulating layer 113 (see FIG. 29A). The charge storage layer 122 can be formed of any of the materials described in the above embodiments. Here, a germanium nitride layer is formed as the charge storage layer 122.

  Next, a resist 123 is selectively formed over the first insulating layer 133 and the second insulating layer 115, and the second insulating layer 115 and the charge storage layer 122 are selectively removed using the resist 123 as a mask. Thus, the second insulating layer 120 and the charge storage layer 126 are formed while the stacked structure of the second insulating layer 115 and the charge storage layer 122 is left. In addition, the charge storage layer 127 is formed by leaving the charge storage layer 122 formed over the first insulating layer 113. Note that the charge storage layer 127 can be removed (see FIG. 29B). The second insulating layer 120 formed in the memory portion functions as a tunnel insulating film in a nonvolatile memory element to be completed later.

  Next, the semiconductor layer 103 is selectively etched to form island-shaped semiconductor layers 104, 106, 108, and 110 (see FIG. 29C).

  Next, a third insulating layer 128 is formed so as to cover the semiconductor layers 104 and 106, the charge storage layer 126 formed above the semiconductor layer 108, and the charge storage layer 127 formed above the semiconductor layer 110 (see FIG. (See FIG. 30A).

  Next, conductive layers 134, 136, 138, and 140 that function as gate electrodes are formed over the semiconductor layers 104, 106, 108, and 110, respectively (see FIG. 30B). Note that the conductive layer 138 formed over the semiconductor layer 108 provided in the memory portion functions as a control gate in a nonvolatile memory element to be completed later. In addition, the conductive layers 134, 136, and 140 function as gate electrodes in a transistor that is completed later.

  Next, as shown in the above embodiment, after forming a channel formation region and an impurity region in the semiconductor layers 104, 106, 108, and 110, respectively, the third insulating layer 128, the conductive layers 134, 136, 138, and 140 are formed. An insulating layer 162 is formed so as to cover the conductive layer 164, and a conductive layer 164 electrically connected to the impurity regions 160, 150, 154, and 146 formed in the semiconductor layers 104, 106, 108, and 110, respectively, is formed over the insulating layer 162. It is formed (see FIG. 30C).

  Note that this example can be implemented in combination with any of the other embodiments and examples shown in this specification.

  In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device using a semiconductor substrate different from the above embodiment will be described with reference to drawings. 37 to 39 are top views, FIGS. 31 to 35 are cross-sectional views taken along lines AB and EF in FIGS. 37 to 39, and FIG. 40 is FIGS. Sectional drawing between CD in FIG. A line between A and B shows a transistor and a non-volatile memory element provided in the memory part, a line between CD and a non-volatile memory element provided in the memory part, and a line between E and F a transistor provided in the logic part. Show. In this embodiment, the transistor provided in the region 1207 of the substrate 1200 between E and F is a p-channel type, the transistor provided in the region 1208 is an n-channel type, and the region 1209 of the substrate 1200 between A and B is used. The case where the transistor provided in the transistor is an n-channel type and the carrier of the nonvolatile memory element is moved by electrons will be described; however, the nonvolatile semiconductor device of the present invention is not limited to this.

  First, an insulating layer is formed over the substrate 1200. Here, single crystal Si having n-type conductivity is used as the substrate 1200, and the insulating layer 1201 and the insulating layer 1202 are formed over the substrate 1200 (see FIG. 31A). For example, silicon oxide is formed as the insulating layer 1201 by performing heat treatment on the substrate 1200, and silicon nitride is formed over the insulating layer 1202 by a CVD method.

  Further, the substrate 1200 can be used without any particular limitation as long as it is a semiconductor substrate. For example, a single crystal Si substrate having an n-type or p-type conductivity, a compound semiconductor substrate (GaAs substrate, InP substrate, GaN substrate, SiC substrate, sapphire substrate, ZnSe substrate, etc.), bonding method or SIMOX (Separation by IMplanted) An SOI (Silicon on Insulator) substrate manufactured using an OXygen method or the like can be used.

  The insulating layer 1202 may be provided by nitriding the insulating layer 1201 by high-density plasma treatment after the insulating layer 1201 is formed. Note that the insulating layer provided over the substrate 1200 may be a single layer or a stacked structure including three or more layers.

  Next, a pattern of a resist mask 1203 is selectively formed over the insulating layer 1202, and selective etching is performed using the resist mask 1203 as a mask, whereby a recess 1204 is selectively formed in the substrate 1200 (FIG. 31). (See (B)). Etching of the substrate 1200 and the insulating layers 1201 and 1202 can be performed by dry etching using plasma.

  Next, after removing the pattern of the resist mask 1203, an insulating layer 1205 is formed so as to fill the concave portion 1204 formed in the substrate 1200 (see FIG. 31C).

  The insulating layer 1205 is formed using an insulating material such as silicon oxide, silicon nitride, silicon nitride containing oxygen, or silicon oxide containing nitrogen by a CVD method, a sputtering method, or the like. Here, as the insulating layer 1205, silicon oxide is formed using TEOS (tetraethylorthosilicate) gas by an atmospheric pressure CVD method or a low pressure CVD method.

  Next, the surface of the substrate 1200 is exposed by performing a grinding process, a polishing process, or a CMP (Chemical Mechanical Polishing) process. Here, regions 1207 to 1209 are provided between the insulating layers 1206 formed in the recesses 1204 of the substrate 1200 by exposing the surface of the substrate 1200. Note that the insulating layer 1206 is obtained by removing the insulating layer 1205 formed over the surface of the substrate 1200 by grinding, polishing, or CMP. Subsequently, an impurity element having p-type conductivity is selectively introduced to form p-wells 1210 in the regions 1208 and 1209 of the substrate 1200 (FIGS. 32A, 37A, and 37B). ), FIG. 40 (A)).

  As the p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, boron (B) is introduced into the regions 1208 and 1209 as the impurity element.

  Note that in this embodiment, since a semiconductor substrate having n-type conductivity is used as the substrate 1200, no impurity element is introduced into the region 1207, but by introducing an impurity element exhibiting n-type conductivity. An n-well may be formed in the region 1207. As the impurity element exhibiting n-type, phosphorus (P), arsenic (As), or the like can be used.

  On the other hand, in the case where a semiconductor substrate having p-type conductivity is used, an n-type impurity element is introduced into the region 1207 to form an n-well, and no impurity element is introduced into the regions 1208 and 1209. It is good.

  Next, the first insulating layer 1211 is formed over the regions 1207 to 1209 provided in the substrate 1200 (see FIG. 32B).

  The first insulating layer 1211 can be formed in a manner similar to that of the first insulating layer 112 described in Embodiment 1. Here, silicon oxynitride is formed as the first insulating layer 1211 by a CVD method.

  Note that the first insulating layer 1211 formed in the exposed region 1209 of the substrate 1200 functions as a gate insulating film in a transistor to be completed later.

  Next, a resist mask 1212 is selectively formed so as to cover the first insulating layer 1211 formed in the region 1209 of the substrate 1200, and the first insulating layer 1211 formed in the regions 1207 and 1208 of the substrate 1200 is formed. The portion of the first insulating layer 1211 provided in the region 1209 is selectively removed, so that the first insulating layer 1213 is formed (see FIG. 32C).

  Next, after the resist mask 1212 is removed, second insulating layers 1214 to 1216 are formed over the surfaces 1207 and 1208 and part of the region 1209 of the substrate 1200, respectively. Next, a charge storage layer 1217 is formed so as to cover the first insulating layer 1213 and the second insulating layers 1214 to 1216. (See FIG. 33A).

  The second insulating layers 1214 to 1216 may be formed using plasma treatment as described above. For example, after the substrate 1200 is heated to oxidize the surfaces of the regions 1207 to 1209 to form a silicon oxide layer, the surface of the silicon oxide layer is subjected to plasma treatment and nitrogen plasma treatment with a high nitrogen concentration on or near the silicon oxide layer surface. Form a layer. Alternatively, after the surface of the regions 1207 to 1209 is oxidized by high-density plasma treatment, nitriding treatment may be performed by performing high-density plasma treatment again. In this case, a silicon oxide layer is formed in contact with the surface of the regions 1207 to 1209, and a nitrogen plasma treatment layer having a high nitrogen concentration is formed at the interface between the silicon oxide layer and the charge storage layer or in the silicon oxide layer near the interface. The That is, the second insulating layers 1214 to 1216 can be formed using a silicon oxide layer having a nitrogen plasma treatment layer with a high nitrogen concentration on the surface or in the vicinity of the surface.

  Alternatively, the second insulating layers 1214 to 1216 can be formed using a silicon oxide layer by performing heat treatment to oxidize the surfaces of the regions 1207 to 1209 provided in the substrate 1200.

  Here, as the second insulating layers 1214 to 1216, the surface of the regions 1207 to 1209 provided in the substrate 1200 is subjected to oxidation treatment by high-density plasma treatment, and then nitridation treatment is performed to obtain a silicon oxide layer and a nitrogen plasma. A treatment layer is laminated and formed.

  In this embodiment, the second insulating layer 1216 formed over the region 1209 provided in the memory portion in the substrate 1200 functions as a tunnel oxide film in a nonvolatile memory element completed later. Therefore, the thinner the second insulating layer 1216 is, the easier it is for the tunnel current to flow and the higher speed operation of the memory becomes possible. Further, as the thickness of the second insulating layer 1216 is thinner, charges can be stored in the charge storage layer 1217 at a lower voltage, so that power consumption of the nonvolatile semiconductor memory device can be reduced. Therefore, the second insulating layer 1216 is preferably formed thin.

  The charge storage layer 1217 includes germanium such as germanium nitride, germanium oxide, germanium nitride to which oxygen is added, germanium oxide to which nitrogen is added, germanium nitride to which oxygen and hydrogen are added, germanium oxide to which nitrogen and hydrogen are added, and the like. Can be formed with compounds. Here, the charge storage layer 1217 is formed in the same manner as the charge storage layer 122 described in Embodiment 1.

  Next, a resist mask 1218 is formed over the charge accumulation layer 1217, and the charge accumulation layer 1217 and the second insulating layers 1214 to 1216 are selectively removed using the resist mask 1218 as a mask. Here, a resist mask 1218 is formed so as to cover part of the region 1209 in the substrate 1200, and the charge storage layer 1217 and the second insulating layers 1214 to 1216 that are not covered with the resist mask 1218 are removed, Part of the second insulating layer 1216 and the charge storage layer 1217 provided in the region 1209 are left to be the second insulating layer 1219 and the charge storage layer 1220 (see FIG. 33B). Specifically, in the region 1209, the second insulating layer 1219 and the charge storage layer 1220 provided in a region where a nonvolatile memory element is to be formed later are left. In addition, regions 1207 and 1208 of the substrate 1200 and a part of the surface of the region 1209 are exposed.

  Next, after removing the resist mask 1218, a third insulating layer 1221 is formed so as to cover the regions 1207 to 1209 and the charge storage layer 1220 of the substrate 1200 (see FIG. 33C).

The third insulating layer 1221 is a single layer or a stacked layer using an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride by a CVD method, a sputtering method, or the like, like the first insulating layer 1211. Form. Here, silicon oxynitride is formed as the third insulating layer 1221 by a CVD method.

Note that the third insulating layer 1221 formed over the charge storage layer 1220 in the region 1209 of the substrate 1200 functions as a control insulating film in a nonvolatile memory element completed later.

  Next, a conductive layer is formed over the third insulating layer 1221 (see FIG. 34A). Here, an example is shown in which a conductive layer 1222 and a conductive layer 1223 are sequentially stacked as the conductive layer. Of course, the conductive layer may be formed of a single layer or a stacked structure of three or more layers.

  The conductive layers 1222 and 1223 can be formed in the same manner as the conductive layers 130 and 132 described in Embodiment 1.

  Here, the conductive layer 1222 is formed using tantalum nitride, and the conductive layer 1223 is formed using tungsten in a stacked structure.

  Next, the conductive layers 1222 and 1223 provided in a stacked manner are selectively etched and removed, so that the conductive layers 1222 and 1223 remain in a part above the regions 1207 to 1209 of the substrate 1200, respectively. Conductive layers 1224-1227 that function as electrodes are formed (see FIGS. 34B and 40B). Here, in the substrate 1200, the surfaces of the regions 1207 to 1209 that do not overlap with the conductive layers 1224-1227 are exposed. Note that the conductive layer 1227 functions as a control gate in a nonvolatile memory element to be completed later.

  Specifically, in a region 1207 of the substrate 1200, a portion of the third insulating layer 1221 formed below the conductive layer 1224 that does not overlap with the conductive layer 1224 is selectively removed, so that the conductive layer 1224 and the third layer The insulating layer 1221 is formed so that the end portions thereof substantially coincide with each other. Further, in a region 1208 of the substrate 1200, a portion of the third insulating layer 1221 formed below the conductive layer 1225 that does not overlap with the conductive layer 1225 is selectively removed, and the conductive layer 1225 and the etched third layer are selectively removed. The insulating layer 1221 is formed so that the end portions thereof substantially coincide with each other. Further, in the region 1209 of the substrate 1200, a portion of the third insulating layer 1221 formed below the conductive layer 1226 that does not overlap with the conductive layer 1226 is selectively removed, and the third layer etched with the conductive layer 1226 is removed. The insulating layer 1221 is formed so that the end portions thereof substantially coincide with each other. In the region 1209 of the substrate 1200, a portion of the third insulating layer 1221, the charge storage layer 1220, and the second insulating layer 1219 formed below the conductive layer 1227 that does not overlap with the conductive layer 1227 is selectively selected. The removed and conductive layer 1227, the etched third insulating layer 1221 (referred to as a third insulating layer 1229), the charge storage layer 1228, and the etched second insulating layer 1219 (with the second insulating layer 1230) It is formed so that the end portions of FIG.

  In this case, the insulating layer or the like that does not overlap with the conductive layers 1224-1227 may be removed simultaneously with the formation of the conductive layers 1224-1227, or the resist mask remaining after the formation of the conductive layers 1224-1227 or the conductive layer The insulating layer or the like that does not overlap with the conductive layers 1224-1227 may be removed using the layers 1224-1227 as a mask.

  Next, an impurity element is selectively introduced into the regions 1207 to 1209 of the substrate 1200, so that low-concentration impurity regions 1231 to 1233 are formed (see FIG. 34C). Here, a low concentration impurity element imparting n-type conductivity is selectively introduced into the regions 1208 and 1209 using the conductive layers 1225 to 1227 as masks to form the low concentration impurity regions 1232 and 1233, and the conductive layer 1224 is formed in the region 1207. As a mask, a low concentration impurity element imparting p-type is selectively introduced to form a low concentration impurity region 1231. As the impurity element imparting n-type conductivity, phosphorus (P), arsenic (As), or the like can be used. As the impurity element imparting p-type conductivity, boron (B), aluminum (Al), gallium (Ga), or the like can be used.

  Next, insulating layers 1234 to 1237 (also referred to as sidewalls) in contact with the side surfaces of the conductive layers 1224 to 1227 are formed. Specifically, a layer containing an inorganic material such as silicon, silicon oxide, or silicon nitride, or a layer containing an organic material such as an organic resin is formed as a single layer or a stacked layer by a plasma CVD method, a sputtering method, or the like. Then, the insulating layer can be selectively etched by anisotropic etching mainly in the vertical direction so as to be in contact with the side surfaces of the conductive layers 1224-1227. Note that the insulating layers 1234 to 1237 are used as masks for doping when an LDD (Lightly Doped Drain) region is formed. In addition, here, the insulating layers 1234 to 1237 are formed so as to be in contact with the side surfaces of the insulating layer and the charge storage layer formed below the conductive layers 1224 to 1227.

  Subsequently, impurity regions 1238 to 1240 functioning as a source region or a drain region are formed by introducing an impurity element into the regions 1207 to 1209 of the substrate 1200 using the insulating layers 1234 to 1237 and the conductive layers 1224 to 1227 as masks. (See FIGS. 35A, 38A, and 38B). Here, impurity regions 1239 and 1240 are formed in regions 1208 and 1209 of the substrate 1200 by introducing an impurity element imparting a high concentration of n-type using the insulating layers 1235 to 1237 and the conductive layers 1225 to 1227 as masks. An impurity region 1238 is formed by introducing an impurity element imparting high concentration p-type into the insulating layer 1234 and the conductive layer 1224 as masks.

  As a result, an impurity region 1238 that forms a source region or a drain region, a low-concentration impurity region 1241 that forms an LDD region, and a channel formation region 1245 are formed in the region 1207 of the substrate 1200. In the region 1208 of the substrate 1200, an impurity region 1239 that forms a source region or a drain region, a low-concentration impurity region 1242 that forms an LDD region, and a channel formation region 1246 are formed. In the region 1209 of the substrate 1200, impurity regions 1240 that form source and drain regions, low-concentration impurity regions 1243 and 1244 that form LDD regions, and channel formation regions 1247 and 1248 are formed.

  Note that in this embodiment, the impurity element is introduced in a state where the regions 1207 to 1209 of the substrate 1200 which do not overlap with the conductive layers 1224-1227 are exposed. Accordingly, channel formation regions 1245 to 1248 formed in the regions 1207 to 1209 of the substrate 1200 can be formed in self-alignment with the conductive layers 1224-1227.

  Next, an insulating layer 1249 is formed so as to cover an insulating layer, a conductive layer, or the like provided over the regions 1207 to 1209 of the substrate 1200, and openings 1250 to 1254 are formed in the insulating layer 1249 (FIG. 35B )reference).

  The insulating layer 1249 can be formed in a manner similar to that of the insulating layer 162 described in Embodiment 1. Here, it is formed using polysilazane.

  Next, conductive layers 1255 to 1259 are formed in the openings 1250 to 1254 by a CVD method, and the conductive layers 1260 to 1263 are selectively formed over the insulating layer 1249 so as to be electrically connected to the conductive layers 1255 to 1259. (See FIGS. 35C, 39A, 39B, and 40C).

  The conductive layers 1255 to 1259 and 1260 to 1263 can be formed in a manner similar to that of the conductive layer 164 described in Embodiment 1. Here, the conductive layers 1255 to 1259 can be formed by selectively growing tungsten (W) by a CVD method.

  Through the above steps, the p-type transistor 1264 formed in the region 1207 of the substrate 1200, the n-type transistor 1265 formed in the region 1208, the n-type transistor 1266 formed in the region 1209, and the nonvolatile memory element 1267 can be obtained.

  Note that insulating layers 1291 to 1295 formed by a selective oxidation method (LOCOS (Local Oxidation of Silicon) method) can be used instead of the insulating layer 1206 functioning as an element isolation region (see FIG. 36).

  This embodiment can be implemented in combination with any of the other embodiments or examples shown in this specification.

  In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device, which is different from the above embodiment, will be described with reference to drawings.

  Through a process similar to that in Embodiment 4, a first insulating layer 1213, second insulating layers 1214 to 1216, and a charge storage layer 1217 are formed over a substrate 1200. Next, a third insulating layer 1271 is formed over the charge storage layer 1217. (See FIG. 41A).

  The third insulating layer 1271 can be formed in a manner similar to that of the third insulating layer 1221 described in Embodiment 4.

  Next, a resist mask 1218 is formed over the third insulating layer 1271, and the third insulating layer 1271, the charge storage layer 1217, and the second insulating layers 1214 to 1216 are selectively formed using the resist mask 1218 as a mask. To remove. A part of the second insulating layer 1216, the charge storage layer 1217, and the third insulating layer 1271 provided in the region 1209 are left, and the second insulating layer 1219, the charge storage layer 1220, and the third insulating layer 1272 are left. (See FIG. 41B).

  After the resist mask 1218 is removed, fourth insulating layers 1273 to 1275 are formed in exposed portions of the regions 1207 to 1209 of the substrate 1200. Similarly to the second insulating layers 1214 and 1215 described in Embodiment 4, the fourth insulating layers 1273 to 1275 are formed by oxidizing the surface of the substrate 1200 by heat treatment or oxidizing or nitriding the surface of the substrate 1200 by plasma treatment. Can be formed. Therefore, the thickness of the fourth insulating layers 1273 to 1275 can be reduced. Further, the fourth insulating layers 1273 and 1274 function as gate insulating films of transistors formed in the logic portion. Therefore, a transistor capable of high speed operation can be manufactured.

  Here, as the fourth insulating layers 1273 to 1275, the surfaces of the regions 1207 to 1209 provided in the substrate 1200 are oxidized by high-density plasma treatment, and then nitridation is performed, so that nitrogen is formed on or near the surface. Silicon oxide having a nitrogen plasma treatment layer having a high concentration is formed.

  Next, conductive layers 1222 and 1223 are formed over the first insulating layer 1213, the third insulating layer 1272, and the fourth insulating layers 1273 to 1275 (see FIG. 41C).

  Next, similarly to Example 4, the conductive layers 1222 and 1223 provided in a stacked manner are selectively removed by etching, and the conductive layers 1222 and 1223 are partially formed above the regions 1207 to 1209 of the substrate 1200. Then, conductive layers 1224-1226 functioning as gate electrodes and conductive layers 1227 functioning as control gates are formed (see FIGS. 42A and 40B). In the region 1209 of the substrate 1200, a portion of the third insulating layer 1221, the charge accumulation layer 1228, and the second insulating layer 1219 that are formed below the conductive layer 1227 is not selectively overlapped with the conductive layer 1227. The conductive layer 1227, the third insulating layer 1229, the charge storage layer 1228, and the second insulating layer 1230 are formed so as to substantially match with each other.

  Next, as in Example 4, the insulating layers 1234 to 1237 in contact with the side surfaces of the conductive layers 1224 to 1227, the impurity regions 1238 to 1240 functioning as the source region or the drain region, and the low-concentration impurity regions 1241 to form the LDD regions 1244 is formed (see FIGS. 42B, 38A, and 38B).

  Next, the insulating layer 1249, the conductive layers 1255 to 1259, and the conductive layers 1260 to 1263 electrically connected to the conductive layers 1255 to 1259 are selectively formed (FIGS. 42C, 39A, and 39A). B), see FIG.

  Through the above steps, the p-type transistor 1274 formed in the region 1207 of the substrate 1200, the n-type transistor 1275 formed in the region 1208, the n-type transistor 1276 formed in the region 1209, and the nonvolatile memory element 1277 can be obtained.

  In this embodiment, conductive layers 1224-1227 functioning as gate electrodes in Embodiments 4 and 5 will be described with reference to FIGS. Here, description will be made using the fourth embodiment, but the present embodiment can also be applied to the fifth embodiment.

  In this embodiment, the conductive layers 1280a to 1280d functioning as gate electrodes have a stacked structure, and a structure in which first layers 1281 to 1284 made of metal nitride and second layers 1285 to 1288 made of metal are stacked. The end of the first layer protrudes outward from the end of the second layer. At this time, a barrier metal can be formed by using a metal nitride for the first layer. In other words, the metal element of the second layer can be prevented from diffusing into the insulating layer functioning as the gate insulating film and the substrate 1200 below the insulating layer.

  When the conductive layers 1280a to 1280d having such shapes are used as gate electrodes, impurity elements 1238 to 1240 functioning as a source region or a drain region are formed at the same time by introducing an impurity element into the regions 1207 to 1209 of the substrate 1200. , Low concentration impurity regions 1241 to 1244 for forming LDD regions can be formed. That is, the first layer region protruding outward from the end of the second layer functions as a mask for the low concentration impurity region. For this reason, the number of steps can be reduced, and the throughput can be improved.

  In this embodiment, an application example of a semiconductor device including the above-described nonvolatile semiconductor memory device of the present invention and capable of inputting and outputting data without contact will be described with reference to the drawings. A semiconductor device in which data can be input / output without contact is also referred to as an RFID tag, an ID tag, an IC tag, an IC chip, an RF tag, a wireless tag, an electronic tag, or a wireless chip depending on the application.

  The semiconductor device 800 has a function of exchanging data without contact, and controls a high frequency circuit 810, a power supply circuit 820, a reset circuit 830, a clock generation circuit 840, a data demodulation circuit 850, a data modulation circuit 860, and other circuits. A control circuit 870, a memory circuit 880, and an antenna 890 are provided (FIG. 44A). The high-frequency circuit 810 is a circuit that receives a signal from the antenna 890 and outputs the signal received from the data modulation circuit 860 from the antenna 890, and the power supply circuit 820 is a circuit that generates a power supply potential from the received signal, and a reset circuit 830. Is a circuit that generates a reset signal, the clock generation circuit 840 is a circuit that generates various clock signals based on the reception signal input from the antenna 890, and the data demodulation circuit 850 demodulates the reception signal to control the circuit 870. The data modulation circuit 860 is a circuit that modulates the signal received from the control circuit 870. As the control circuit 870, for example, a code extraction circuit 910, a code determination circuit 920, a CRC determination circuit 930, and an output unit circuit 940 are provided. The code extraction circuit 910 is a circuit that extracts a plurality of codes included in the instruction sent to the control circuit 870, and the code determination circuit 920 compares the extracted code with a code corresponding to a reference. The CRC determination circuit 930 is a circuit that detects the presence or absence of a transmission error or the like based on the determined code.

  Next, an example of operation of the above-described semiconductor device will be described. First, a radio signal is received by the antenna 890. The wireless signal is sent to the power supply circuit 820 via the high frequency circuit 810, and a high power supply potential (hereinafter referred to as VDD) is generated. VDD is supplied to each circuit included in the semiconductor device 800. The signal sent to the data demodulation circuit 850 via the high frequency circuit 810 is demodulated (hereinafter, demodulated signal). Further, the signal passing through the reset circuit 830 and the demodulated signal passing through the clock generation circuit 840 are sent to the control circuit 870 via the high frequency circuit 810. The signal sent to the control circuit 870 is analyzed by the code extraction circuit 910, the code determination circuit 920, the CRC determination circuit 930, and the like. Then, information on the semiconductor device stored in the memory circuit 880 is output in accordance with the analyzed signal. The output semiconductor device information is encoded through the output unit circuit 940. Further, the encoded information of the semiconductor device 800 passes through the data modulation circuit 860 and is transmitted on the radio signal by the antenna 890. Note that a low power supply potential (hereinafter referred to as VSS) is common in the plurality of circuits included in the semiconductor device 800, and VSS can be GND. Further, the nonvolatile semiconductor memory device of the present invention can be applied to the memory circuit 880. In the nonvolatile semiconductor memory device of the present invention, since the driving voltage can be lowered, it is possible to extend the distance in which data can be communicated without contact.

  As described above, by transmitting a signal from the reader / writer to the semiconductor device 800 and receiving the signal transmitted from the semiconductor device 800 by the reader / writer, the data of the semiconductor device can be read.

  In addition, the semiconductor device 800 may be a type in which the power supply voltage is supplied to each circuit by an electromagnetic wave without mounting a power supply (battery), or each power supply (battery) is mounted and electromagnetic waves and the power supply (battery) are used. The circuit may be a type that supplies a power supply voltage to the circuit.

  Next, an example of a usage pattern of a semiconductor device capable of inputting and outputting data without contact will be described. A reader / writer 3200 is provided on the side surface of the portable terminal including the display portion 3210, and a semiconductor device 3230 is provided on the side surface of the article 3220 (FIG. 44B). When the reader / writer 3200 is held over the semiconductor device 3230 included in the product 3220, information about the product such as the description of the product, such as the raw material and origin of the product, the inspection result for each production process and the history of the distribution process, is displayed on the display unit 3210. Is done. Further, when the product 3260 is conveyed by the belt conveyor, the product 3260 can be inspected using the reader / writer 3240 and the semiconductor device 3250 provided in the product 3260 (FIG. 44C). In this manner, by using a semiconductor device in the system, information can be easily acquired, and high functionality and high added value are realized.

  In addition, the nonvolatile semiconductor memory device of the present invention can be used for electronic devices in various fields equipped with a memory. For example, as an electronic device to which the nonvolatile semiconductor memory device of the present invention is applied, a camera such as a video camera or a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproduction device (car audio, audio component, etc.), Plays back recording media such as computers, game machines, portable information terminals (mobile computers, mobile phones, portable game machines or electronic books), and image playback devices (specifically DVDs (digital versatile discs)) equipped with recording media And an apparatus provided with a display capable of displaying the image). Specific examples of these electronic devices are shown in FIGS.

  45A and 45B show a digital camera. FIG. 45B is a diagram showing the back side of FIG. This digital camera includes a housing 2111, a display portion 2112, a lens 2113, operation keys 2114, a shutter button 2115, and the like. In addition, a removable nonvolatile memory 2116 is provided, and data captured by the digital camera is stored in the memory unit 2116. A nonvolatile semiconductor memory device formed using the present invention can be applied to the memory portion 2116.

  FIG. 45C illustrates a mobile phone, which is a typical example of a mobile terminal. This mobile phone includes a housing 2121, a display portion 2122, operation keys 2123, and the like. In addition, the mobile phone includes a removable nonvolatile memory 2125, and data such as a phone number of the mobile phone, video, music data, and the like can be stored in the memory 2125 and played back. A nonvolatile semiconductor memory device formed using the present invention can be applied to the memory portion 2125.

  FIG. 45D illustrates a digital audio player, which is a typical example of an audio device. A digital audio player shown in FIG. 45D includes a main body 2130, a display portion 2131, a memory portion 2132, an operation portion 2133, an earphone 2134, and the like. Note that headphones or wireless earphones can be used instead of the earphones 2134. As the memory portion 2132, a nonvolatile semiconductor memory device formed using the present invention can be used. For example, by using a NAND nonvolatile memory with a recording capacity of 20 to 200 gigabytes (GB) and operating the operation unit 2133, video and audio (music) can be recorded and reproduced. Note that the display unit 2131 can reduce power consumption by displaying white characters on a black background. This is particularly effective in a portable audio device. Note that the nonvolatile semiconductor memory device provided in the memory portion 2132 may be removable.

  FIG. 45E illustrates an electronic book (also referred to as electronic paper). This electronic book includes a main body 2141, a display portion 2142, operation keys 2143, a memory portion 2144, and the like. Further, a modem may be incorporated in the main body 2141 or a configuration in which information can be transmitted and received wirelessly may be employed. As the memory portion 2144, a nonvolatile semiconductor memory device formed using the present invention can be used. For example, by using a NAND nonvolatile memory with a recording capacity of 20 to 200 gigabytes (GB) and operating the operation key 2143, video and audio (music) can be recorded and reproduced. Note that the nonvolatile semiconductor memory device provided in the memory portion 2144 may be removable.

  As described above, the applicable range of the nonvolatile semiconductor memory device of the present invention is so wide that it can be used for electronic devices in various fields as long as it has a memory.

It is sectional drawing for demonstrating the main structures of the non-volatile semiconductor memory device based on this invention. It is a band figure of the non-volatile memory element in an initial state (charge discharge state). It is a band figure of the non-volatile memory element in a writing state. It is a band figure of the non-volatile memory element in a charge retention state. It is a band diagram of the nonvolatile memory element in the erased state. It is a figure explaining write-in and read-out operation of a non-volatile memory element. It is a figure explaining erase operation of a non-volatile memory element. It is a figure which shows an example of the equivalent circuit of a non-volatile memory cell array. It is a figure which shows an example of the equivalent circuit of a NOR type non-volatile memory cell array. It is a figure which shows an example of the equivalent circuit of a NAND type non-volatile memory cell array. It is a figure explaining write-in operation of NAND type non-volatile memory. It is a figure explaining erasure | elimination and read-out operation | movement of NAND type non-volatile memory. It is a figure which shows the change of the threshold voltage of a non-volatile memory element in the case of "0" with which charge was accumulate | stored, and the case of "1" erased. It is a figure which shows an example of the circuit block diagram of a non-volatile semiconductor memory device. It is a figure explaining the structure of a plasma processing apparatus. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the manufacturing method of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the non-volatile semiconductor memory device of this invention. It is a figure which shows the usage condition of the non-volatile semiconductor memory device of this invention. It is a figure which shows an example of the upper surface of the non-volatile semiconductor memory device of this invention. It is a figure explaining write-in and read-out operation of a non-volatile memory element. It is a figure explaining erase operation of a non-volatile memory element. It is a figure explaining erasure | elimination and read-out operation | movement of NAND type non-volatile memory.

Claims (2)

A semiconductor region;
A first insulating layer above the semiconductor region;
A charge storage layer above the first insulating layer;
A second insulating layer above the charge storage layer;
A control gate electrode above the second insulating layer,
The charge storage layer includes a germanium compound containing hydrogen and having an insulating property,
The control gate electrode includes a metal and a metal nitride provided between the metal and the second insulating layer. A semiconductor region;
A first insulating layer above the semiconductor region;
A charge storage layer above the first insulating layer;
A second insulating layer above the charge storage layer;
A control gate electrode above the second insulating layer;
A third insulating layer covering an end portion of the semiconductor region,
The charge storage layer includes a germanium compound containing hydrogen and having an insulating property,
The control gate electrode, possess a metal, and a metal nitride provided between said metal second insulating layer,
The third dielectric layer, wherein a different layer der Rukoto from the first insulating layer and said second insulating layer.

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