JP5222478B2 - Method for manufacturing nonvolatile semiconductor memory device - Google Patents

Description

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

  As one of semiconductor memories, the market of nonvolatile memories that can electrically rewrite data and store data even when the power is turned off is expanding. The non-volatile memory has a structure similar to that of a MOS transistor, and is characterized in that a region in which charges can be stored for a long time is provided on a channel formation region. A floating gate type nonvolatile memory is one in which charges are injected and held in a floating gate through a tunnel insulating film on a channel formation region. In a MONOS (Metal-Oxide-Nitride-Oxide Semiconductor) type nonvolatile memory, a trap or silicon cluster of a silicon nitride film is used as a charge holding carrier.

  FIG. 16 shows a typical structure of a nonvolatile memory. The nonvolatile memory includes a first insulating film 801 also called a tunnel insulating film, a charge storage layer 802 also called a floating gate, a second insulating film 803, a control gate electrode 804, a source, and a semiconductor film 800 that form a channel formation region. 805 and a drain 806.

  Such a nonvolatile memory can store 1-bit data with one transistor. In the case of writing data, a voltage is applied between the source 805 and the drain 806, and between the semiconductor film 800 and the control gate electrode 804, and charges are injected from the semiconductor film 800 into the charge storage layer 802 through the first insulating film 801. Then, charges are accumulated in the charge accumulation layer 802 that is electrically insulated from the surroundings. When reading data, the threshold voltage of the MOS transistor changes depending on the presence or absence of charge in the charge storage layer 802, so that information can be read using this characteristic. That is, information of “0” and “1” can be stored and read. When erasing data, conversely, a high voltage is applied to the semiconductor film 800 or the source 805 to extract charges from the charge storage layer 802 through the first insulating film 801.

  Charge injection into the charge storage layer 802 is performed by increasing the voltage applied between the semiconductor film 800 and the control gate electrode 804 and flowing through the first insulating film 801 by a strong electric field (Fowler-Nordheim) type (F− N-type) tunnel current (NAND type) and thermal electrons (NOR type). In any case, a high electric field is applied between the semiconductor film 800 and the control gate electrode 804, and charges are injected into the thin insulating film.

The nonvolatile memory having the charge storage layer 802 is required to have a characteristic capable of holding the charge stored in the charge storage layer 802 for more than 10 years in order to guarantee reliability. Therefore, the first insulating film 801 and the second insulating film 803 are required to have high insulating properties so that charges do not leak from the charge storage layer 802. In the floating gate type nonvolatile memory, it is difficult to make the first insulating film 801 thin in order to flow an FN type tunnel current ( _{7 to 8} nm with a SiO ₂ film), and the write voltage and the erase voltage are low. It is difficult to achieve (10-20V). In addition, in the MONOS type nonvolatile memory, a relatively large volume is required in the silicon nitride film in order to hold charges in traps or silicon clusters in the silicon nitride film and to change the threshold voltage of the MOS transistor. . Therefore, it is considered that there is a limit to miniaturization of elements, and there is a limit to reducing the voltage.

In order to lower the write voltage and improve the charge retention characteristics of the nonvolatile memory, the second insulating film 803 in FIG. 16 is composed of a plurality of insulating films, and a deep trap level is provided at a high concentration. (For example, refer to Patent Document 1). In addition, in a MONOS type nonvolatile memory, one in which charge retention characteristics are improved by controlling the hydrogen concentration of silicon nitride used for the charge storage layer 802 is known (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 11-40682 JP 2004-221448 A

  However, even if the second insulating film 803 and the charge storage layer 802 in FIG. 16 are improved, there is a limit to reducing the thickness of the first insulating film 801 in order to maintain the charge retention characteristics. There still remained a problem that the write voltage could not be lowered if it could not be done. Further, even if only the charge retention characteristics of the charge storage layer 802 are improved, the writing voltage cannot be lowered.

  In the case where a nonvolatile semiconductor memory device is formed using an element such as a thin film transistor over a substrate having low heat resistance such as glass, it is difficult to use a thermal oxidation method for forming an insulating film. Therefore, when forming the first insulating film 801 thin, it is necessary to form the first insulating film 801 with a film thickness of several nm by a CVD method or a sputtering method. However, the first insulating film 801 formed with a film thickness of several nm by the CVD method or the sputtering method has defects inside the film and the film quality is not sufficient. Therefore, the leakage current is generated or the semiconductor film 800 and the charge storage layer 802 are formed. Or the like occurs, and the reliability of the nonvolatile semiconductor memory device is reduced (writing or reading failure).

  In view of the above problems, an object of the present invention is to provide a nonvolatile semiconductor memory device that can perform high-efficiency writing at a low voltage and has excellent charge retention characteristics, and a manufacturing method thereof.

  A nonvolatile semiconductor memory device according to the present invention includes a semiconductor film having a pair of impurity regions formed apart from each other and a channel formation region therebetween, a first insulating film provided above the channel formation region, a charge A storage layer, a second insulating film, and a conductive film functioning as a gate electrode layer, and a first barrier for the charge of the charge storage layer with respect to the first barrier formed by the first insulating film for the charge of the semiconductor film. The second barrier formed by the insulating film is high in energy.

  A nonvolatile semiconductor memory device according to the present invention includes a semiconductor film having a pair of impurity regions formed apart from each other and a channel formation region therebetween, a first insulating film provided above the channel formation region, a charge The charge storage layer is formed of a material having a storage layer, a second insulating film, and a conductive film functioning as a gate electrode layer, and having a smaller energy gap (band gap) or a higher electron affinity than the semiconductor film. It is characterized by being.

  According to the method for manufacturing a nonvolatile semiconductor memory device of the present invention, a semiconductor film is formed over a substrate and a high-density plasma treatment is performed, whereby a first insulating film containing one or both of oxygen and nitrogen on the surface of the semiconductor film A charge storage layer having a material with a smaller energy gap than the semiconductor film or a material with a higher electron affinity is formed on the first insulating film, and a second insulating film containing nitrogen is formed on the charge storage layer. A conductive film is formed over the second insulating film, a resist is selectively formed over the semiconductor film, and the first insulating film, the charge storage layer, the second insulating film, and the conductive film are selectively formed. Then, the first insulating film, the charge storage layer, the second insulating film, and the conductive film are left so as to overlap with at least part of the semiconductor film, and an impurity element is introduced using the remaining conductive film as a mask. Impurities in the semiconductor film It is characterized by forming the region.

  According to the method for manufacturing a nonvolatile semiconductor memory device of the present invention, a semiconductor film is formed over a substrate, a first high-density plasma treatment is performed in an oxygen atmosphere, and then a second high-density plasma is performed in a nitrogen atmosphere. By performing the treatment, a first insulating film including a stacked film of an oxide film and a film containing oxygen and nitrogen is formed on the surface of the semiconductor film, and a material having an energy gap smaller than that of the semiconductor film is formed on the first insulating film; Alternatively, a charge storage layer having a material with a high electron affinity is formed, a second insulating film containing nitrogen is formed over the charge storage layer, and a third high-density plasma treatment is performed in an oxygen atmosphere, whereby nitrogen is removed. The surface of the second insulating film is oxidized, a conductive film is formed on the oxidized second insulating film, and the first insulating film, the charge storage layer, the second insulating film, and the conductive film are selected. By removing The first insulating film, the charge storage layer, the second insulating film, and the conductive film are left to overlap with at least part of the conductor film, and an impurity element is introduced into the semiconductor film using the remaining conductive film as a mask. An impurity region is formed.

  The method for manufacturing a nonvolatile semiconductor memory device of the present invention is continued after forming a first semiconductor film and a second semiconductor film on a substrate and performing a first high-density plasma treatment in an oxygen atmosphere. By performing the second high-density plasma treatment in a nitrogen atmosphere, a first insulating film is formed on the surface of the first semiconductor film and the surface of the second semiconductor film, and the first insulating film is formed on the first insulating film. A charge storage layer having a material with a smaller energy gap than that of the semiconductor film and the second semiconductor film or a material with a higher electron affinity is formed, and a second insulating film containing nitrogen is formed on the charge storage layer. The first insulating film, the charge storage layer, and the second insulating film formed on the first semiconductor film are selectively removed to expose the surface of the second semiconductor film, and a third high density is obtained in an oxygen atmosphere. By performing plasma treatment, the first semiconductor film At the same time that the surface of the second insulating film containing nitrogen formed above is oxidized, a gate insulating film is formed on the surface of the second semiconductor film, and the surface of the oxidized second insulating film and the gate insulating film are oxidized. A conductive film is formed thereover, and the first insulating film, the charge storage layer, the second insulating film, the gate insulating film, and the conductive film are selectively removed to overlap with at least part of the first semiconductor film. As described above, the first insulating film, the charge storage layer, the second insulating film, and the conductive film are left, and the gate insulating film and the conductive film are left so as to overlap at least part of the second semiconductor film. An impurity region is formed in the first semiconductor film and the second semiconductor film by introducing an impurity element using the film as a mask.

  In the nonvolatile semiconductor memory device of the present invention, the semiconductor film may be formed on a substrate having an insulating surface. In the nonvolatile semiconductor memory device of the present invention, the pair of impurity regions and the channel formation region may be formed on a single crystal silicon substrate.

Note that the high-density plasma treatment is performed using high frequency under conditions where the electron density is 1 × 10 ¹¹ cm ⁻³ or more and 1 × 10 ¹³ cm ⁻³ or less and the electron temperature is 0.5 eV or more and 1.5 eV or less. It is plasma processing.

  In the case where the charge storage layer is formed on the semiconductor film via the insulating film functioning as a tunnel oxide film, the insulating film for the charge of the charge storage layer is formed with respect to the first barrier formed by the insulating film for the charge of the semiconductor film. By adopting a structure in which the formed second barrier is high in energy, it is possible to easily inject charges from the semiconductor film to the charge storage layer and to prevent the charge from being lost from the charge storage layer.

  In addition, when a charge storage layer is formed on a semiconductor film via an insulating film functioning as a tunnel oxide film, the charge storage layer is formed using a material having a smaller energy gap than that of the semiconductor film or a material having a higher electron affinity. By providing, it is possible to easily inject charges from the semiconductor film into the charge storage layer and to prevent the charge from being lost from the charge storage layer. As a result, high-efficiency writing can be performed at a low voltage, and a highly reliable nonvolatile semiconductor memory device having excellent charge retention characteristics can be manufactured.

  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.

(Embodiment 1)
In this embodiment, an example of a nonvolatile semiconductor memory device is described with reference to drawings. Note that here, a memory element that constitutes a memory portion in a nonvolatile semiconductor memory device, a transistor that constitutes a logic portion that is provided on the same substrate as the memory portion and performs control of writing to and reading from the memory element, and the like The case where these elements are simultaneously formed is shown.

First, island-shaped semiconductor films 103a and 103b are formed over the substrate 101 with the insulating film 102 interposed therebetween (FIG. 1A). The island-shaped semiconductor films 103a and 103b are formed using a material (for example, Si _x ) containing silicon (Si) as a main component by using a sputtering method, an LPCVD method, a plasma CVD method, or the like over the insulating film 102 formed in advance on the substrate 101. An amorphous semiconductor film can be formed using Ge _1-x or the like, and the amorphous semiconductor film can be crystallized and then selectively etched. The crystallization of the amorphous semiconductor film is 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.

  The substrate 101 is selected from a glass substrate, a quartz substrate, a metal substrate (for example, a stainless steel substrate), a semiconductor substrate such as a ceramic substrate, and a Si substrate. In addition, as the plastic substrate, a substrate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfine (PES), or acrylic can be selected.

  As the insulating film 102, silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy) (x> y> 0), silicon nitride oxide (SiNxOy) (x) is used by a CVD method, a sputtering method, or the like. > Y> 0) or the like. For example, in the case where the insulating film 102 has a two-layer structure, a silicon nitride oxide film may be formed as the first insulating film and a silicon oxynitride film may be formed as the second insulating film. Alternatively, a silicon nitride film may be formed as the first insulating film, and a silicon oxide film may be formed as the second insulating film. In this manner, by forming the insulating film 102 functioning as a blocking layer, an alkali metal such as Na or an alkaline earth metal from the substrate 101 can be prevented from adversely affecting an element formed thereon. Note that the insulating film 102 may be omitted when quartz is used for the substrate 101.

  Next, by performing high-density plasma treatment and performing oxidation treatment, nitridation treatment, or oxynitridation treatment on the semiconductor films 103a and 103b, an oxide film, a nitride film, or oxygen and nitrogen are formed on the surfaces of the semiconductor films 103a and 103b, respectively. A first insulating film 104 (hereinafter referred to as an insulating film 104) is formed (FIG. 1B).

  For example, in the case where oxidation treatment or nitridation treatment is performed using a semiconductor film containing Si as a main component as the semiconductor films 103a and 103b, a silicon oxide film and a silicon nitride film are formed as the insulating film 104. Further, after the semiconductor films 103a and 103b 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 film is formed in contact with the semiconductor films 103a and 103b, a film containing oxygen and nitrogen (oxynitride film) is formed over the silicon oxide film, and the insulating film 104 includes the silicon oxide film and the oxynitride film. Is a laminated film.

  Here, the insulating film 104 is formed with a thickness of 1 to 10 nm, preferably 1 to 5 nm. For example, a silicon oxide film having a thickness of about 5 nm is formed on the surfaces of the semiconductor films 103a and 103b by performing oxidation treatment on the semiconductor films 103a and 103b by high-density plasma treatment, and then approximately on the surface of the silicon oxide film by high-density plasma treatment. A 2 nm oxynitride film is formed. In this case, the thickness of the silicon oxide film formed on the surfaces of the semiconductor films 103a and 103b is approximately 3 nm. This is because the oxynitride film is reduced by the amount 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.

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

  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 insulating film 104 may contain a rare gas (including at least one of He, Ne, Ar, Kr, and Xe) used for the plasma treatment. , Ar may be contained in the insulating film 104 in some cases.

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 plasma is high and the electron temperature in the vicinity of the object to be processed (here, the semiconductor films 103a and 103b) formed on the substrate 101 is low, the object to be processed is prevented from being damaged by the plasma. Can do. In addition, since the electron density of plasma is as high as 1 × 10 ¹¹ cm ⁻³ or higher, an oxide film or a nitride film formed by oxidizing or nitriding an object to be irradiated using plasma treatment is a CVD method. Compared with a film formed by sputtering or the like, a film having excellent uniformity in film thickness and the like and a dense film 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 lower than 100 degrees below 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, the insulating film 104 formed over the semiconductor film 103a in the memory portion functions as a tunnel oxide film in a memory element to be completed later. Therefore, the thinner the insulating film 104 is, the easier it is for the tunnel current to flow, and the memory can operate at high speed. In addition, as the insulating film 104 is thinner, charges can be stored in a charge storage layer formed later at a lower voltage, so that power consumption of the semiconductor device can be reduced. Therefore, the insulating film 104 is preferably formed thin.

  In general, there is a thermal oxidation method as a method for forming a thin insulating film on a semiconductor film. However, when a memory element is provided on a substrate such as a glass substrate whose melting point is not sufficiently high, the insulating film is formed by a thermal oxidation method. Forming 104 is very difficult. In addition, an insulating film formed by a CVD method or a sputtering method includes defects inside the film, so that the film quality is not sufficient, and there is a problem that defects such as pinholes occur when the film thickness is thin. In addition, in the case where an insulating film is formed by a CVD method or a sputtering method, the end portion of the semiconductor film is not sufficiently covered, and the conductive film or the like formed later on the insulating film 104 is in contact with the semiconductor film and leaks. There is a case. Therefore, as shown in this embodiment mode, by forming the insulating film 104 by high-density plasma treatment, an insulating film denser than an insulating film formed by a CVD method, a sputtering method, or the like can be formed. The end portion of the semiconductor film can be sufficiently covered with the insulating film. As a result, the memory can be operated at high speed, and the power consumption of the semiconductor device can be reduced.

  Next, the charge storage layer 105 is formed over the insulating film 104 (FIG. 1C). The charge storage layer 105 functions as a charge storage layer in a memory element to be completed later, and is generally called a floating gate (floating gate). For the charge storage layer 105, a material having an energy gap (band gap) smaller than that of the material used for the semiconductor films 103a and 103b is preferably used. For example, germanium (Ge), a silicon germanium alloy, or the like can be used. In addition, any other conductive film or semiconductor film can be used as the charge storage layer 105 as long as the material has a smaller energy gap (band gap) than the material used for the semiconductor films 103a and 103b. For the charge storage layer 105, a material having higher electron affinity than the material used for the semiconductor films 103a and 103b may be used.

Here, as the charge storage layer 105, a plasma CVD method is performed in an atmosphere containing a germanium element (for example, GeH ₄ ) to form a film containing germanium as a main component with a thickness of 1 to 20 nm, preferably 5 to 10 nm. . As described above, a film containing germanium having a smaller energy gap than Si is formed on the semiconductor film with an insulating film functioning as a tunnel oxide film formed using a material mainly containing Si as a semiconductor film. The second barrier formed by the insulating film for the charge of the charge storage layer is energetically higher than the first barrier formed by the insulating film for the charge of the semiconductor film. As a result, charges can be easily injected from the semiconductor film into the charge storage layer, and the charge can be prevented from disappearing from the charge storage layer. That is, when operating as a memory, high-efficiency writing can be performed at a low voltage, and charge retention characteristics can be improved.

  Next, a second insulating film 107 including a silicon oxynitride film, a silicon nitride film, a silicon nitride oxide film, or the like is formed over the charge storage layer 105 (FIG. 1D). The insulating film 107 can be formed by an LPCVD method, a plasma CVD method, or the like. Here, a silicon nitride film or a silicon nitride oxide film is formed as the insulating film 107 by a plasma CVD method in an amount of 1 to 20 nm, preferably 5 to 10 nm. Form with. Further, the charge storage layer 105 is subjected to high-density plasma treatment, and the surface of the charge storage layer 105 is nitrided to form a nitride film (for example, when a film containing germanium as a main component is used as the charge storage layer 105). , GeNx) may be formed. In this case, a nitride film obtained by nitriding treatment may be used as the insulating film 107, or the insulating film described above may be separately formed as the insulating film 107 on the nitride film obtained by nitriding treatment. In addition, the second insulating film 107 may be formed using aluminum oxide (AlOx), hafnium oxide (HfOx), or tantalum oxide (TaOx).

  Note that in the above steps, it is preferable that the charge storage layer 105 and the insulating film 107 be continuously formed without being exposed to the atmosphere. By continuously forming the charge storage layer 105 and the insulating film 107, contamination can be prevented and production efficiency can be improved. For example, the charge storage layer 105 and the insulating film 107 are continuously formed without being exposed to the atmosphere by plasma CVD.

  Next, after a resist 108 is selectively formed so as to cover the elements constituting the memory portion, the insulating film 104, the charge storage layer 105, and the insulating film 107 formed above the elements constituting the logic portion are selectively formed. (FIG. 1E). Here, after a resist 108 is selectively formed so as to cover the insulating film 107 formed above the semiconductor film 103a, the insulating film 104, the charge storage layer 105, and the insulating film 107 formed above the semiconductor film 103b. Are selectively removed to expose the semiconductor film 103b.

  Next, high-density plasma treatment is performed, and oxidation treatment, nitridation treatment, or oxynitridation treatment is performed (FIG. 2A). As a result, the insulating film 110 is formed on the surface of the second insulating film 107, and the insulating film 109 is formed on the surface of the semiconductor film 103b. Here, the insulating film 107 formed of a silicon nitride film or a silicon nitride oxide film is subjected to high-density plasma treatment in an oxygen atmosphere, whereby an oxynitride film (here, a silicon nitride oxide film or a silicon oxide film) is formed on the surface of the insulating film 107. An insulating film 110 having a silicon oxynitride film) is formed. At the same time, an insulating film 109 including a silicon oxide film is formed on the surface of the semiconductor film 103b. The insulating film 109 functions as a gate insulating film. Note that the insulating film 110 may not be formed by covering the second insulating film 107 with a mask or the like. Note that the high-density plasma treatment may be performed in the same manner as in the condition and method in which the semiconductor films 103a and 103b are subjected to the high-density plasma treatment in FIG.

  In FIG. 2A, the insulating film 109 may be formed by a plasma CVD method or the like instead of performing high density plasma treatment. In this case, an insulating film may or may not be formed over the second insulating film 107.

  Next, a conductive film is formed over the semiconductor film 103a and the semiconductor film 103b (FIG. 2B). Here, an example in which the conductive film 111a and the conductive film 111b are stacked is shown as the conductive film. Needless to say, the conductive film may be formed of a single layer or a stacked structure of three or more layers.

  The conductive films 111a and 111b 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 semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus can be used. Here, the conductive film 111a is formed using tantalum nitride, and the conductive film 111b is formed using tungsten in a stacked structure. In addition, tungsten nitride, molybdenum nitride, or titanium nitride can be used as the conductive film 111a, and tantalum, molybdenum, titanium, or the like can be used as the conductive film 111b. The conductive film 111a can be formed by freely combining these materials. In addition, the conductive film 111b can be formed.

  Next, a resist 112 is selectively formed over the conductive film 111b formed over the semiconductor films 103a and 103b, and the insulating film 104 and the charge storage layer provided over the semiconductor film 103a are formed using the resist 112 as a mask. 105, the insulating film 107, the insulating film 110, the conductive film 111a, the conductive film 111b, and the insulating film 109, the conductive film 111a, and the conductive film 111b provided over the semiconductor film 103b are selectively removed (FIG. 2C )).

  Next, an impurity element is introduced into the semiconductor film 103a and the semiconductor film 103b, whereby the impurity region 114a which functions as a source region or a drain region is separated from the semiconductor film 103a and the semiconductor film 103b. A channel formation region 114b is formed therebetween (FIG. 2D). Note that when the impurity element is introduced into the semiconductor films 103a and 103b, the impurity regions 114a and the channel formation region 114b are formed in a self-aligned manner (self-alignment) by using the conductive films 113a and 113b functioning as gate electrodes as masks. Can be formed.

  Next, an insulating film is formed over the semiconductor films 103a and 103b and the conductive films 113a and 113b (FIG. 2E). Here, an example is shown in which an insulating film 115a and an insulating film 115b are stacked as the insulating film. Note that the insulating film may be formed with a single layer or a stacked structure of three or more layers. Thereafter, contact holes are selectively formed in the insulating films 115a and 115b to expose the semiconductor films 103a and 103b, and a conductive film 116 is selectively formed so as to fill the contact holes. The conductive film 116 is electrically connected to the impurity regions 114a of the semiconductor films 103a and 103b.

  Through the above steps, a nonvolatile semiconductor memory device including a memory element portion having a memory element and a logic portion can be manufactured. In the manufacturing method illustrated in FIGS. 1 and 2, the insulating film 104 and the insulating film 109 can be provided with different thicknesses or different materials.

  Note that although an example in which a thin film transistor (TFT) is formed using a semiconductor film formed over a substrate is described in this embodiment mode, the nonvolatile semiconductor memory device of the present invention is not limited to this. For example, as shown in FIG. 8, a field effect transistor (FET) in which a channel formation region is directly formed on a substrate using a semiconductor substrate such as Si may be used.

  The field effect transistor is formed over the single crystal semiconductor substrate 301. Single crystal semiconductor substrate 301 has n well or p well 302 formed therein and is separated by field oxide film 303. Further, it is preferable that a p-well is provided when an n-type single crystal semiconductor substrate is used, and only an n-well is provided when a p-type single crystal semiconductor substrate is used. The gate insulating films 304 to 305 are thin films formed by high-density plasma treatment or thermal oxidation. The charge storage layer 105, the insulating film 107, the insulating film 110, the conductive films 113a, 113b, and 116 can be formed using the materials and methods described in this embodiment.

  As described above, when the charge storage layer is formed on the semiconductor film via the insulating film functioning as a tunnel oxide film, the charge storage layer is not exposed to the first barrier formed by the insulating film with respect to the charge of the semiconductor film. By adopting a structure in which the second barrier formed by the insulating film against charges is high in energy, it is easy to inject charges from the semiconductor film to the charge storage layer and prevent the charge from disappearing from the charge storage layer. it can. In addition, when a charge storage layer is formed on a semiconductor film via an insulating film functioning as a tunnel oxide film, the charge storage layer is provided using a material having an energy gap (band gap) smaller than that of the semiconductor film. Further, it is possible to easily inject charges from the semiconductor film into the charge storage layer and to prevent the charge from being lost from the charge storage layer. As a result, high-efficiency writing can be performed at a low voltage, and a nonvolatile semiconductor memory device having excellent charge retention characteristics can be manufactured.

(Embodiment 2)
In this embodiment, injection and retention of charges in the charge storage layer in the memory portion of the nonvolatile semiconductor memory device described in the above embodiment are described with reference to FIGS.

  FIG. 15 shows a band diagram of the memory element of Embodiment Mode 1. The semiconductor film 103a, the first insulating film 104, the charge storage layer 105, the second insulating film 107 (or the second insulating film 107). And a conductive film 113a functioning as a gate electrode are stacked. Note that FIG. 15 illustrates the case where the semiconductor film 103a is p-type.

  FIG. 15A illustrates a case where no voltage is applied to the conductive film 113a, and the Fermi level Ef of the semiconductor film 103a is equal to the Fermi level Efm of the conductive film 113a. FIG. 15B shows the case where a voltage is applied to the conductive film 113 a and electrons are held in the charge storage layer 105.

  The semiconductor film 103a and the charge storage layer 105 are formed using different materials with the first insulating film 104 interposed therebetween. In this case, the band gap of the semiconductor film 103a (energy difference between the lower end Ec of the conduction band and the upper end Ev of the valence band) is different from the band gap of the charge storage layer 105, and the latter band gap is combined to be small. For example, when the semiconductor film 103a is silicon (1.12 eV), the charge storage layer 105 can be a combination of germanium (0.72 eV) and silicon germanium (0.73 to 1.1 eV). In this case, the energy barrier against electrons, that is, the first barrier Be1 and the second barrier Be2 have different values and have a relationship of Be2> Be1.

  In order to inject electrons into the charge storage layer 105, 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 conductive film 113a functioning as a gate electrode. In this state, when a high voltage is applied to the drain to generate thermoelectrons, thermoelectrons that can overcome the first barrier can be injected into the charge storage layer 105. When the FN type tunnel current is used, it is not necessary to give the electrons energy over the first barrier, and the electrons are injected into the charge storage layer 105 by the quantum mechanical tunnel phenomenon.

  While electrons are held in the charge storage layer 105, the threshold voltage of the transistor shifts to the positive side. This state can be a state in which information “0” is written. This “0” information can be detected by detecting that the transistor is not turned on by a sense circuit when a gate voltage that turns on the transistor is applied in a state where no charge is held in the charge storage layer 105.

  The retention characteristics of the electrons stored in the charge storage layer 105 are important, but by increasing the second barrier Be2, the electrons flowing into the semiconductor film 103a due to the quantum mechanical tunnel current are probabilistically reduced. Further, electrons flowing into the conductive film 113a through the second insulating film 104 can be reduced. That is, as a method for holding the electrons accumulated in the charge storage layer 105 for a long period of time, the height of the second barrier Be2 is made larger than that of the first barrier Be1, thereby holding the memory without applying voltage to the conductive film 113a. In this state, the charge can be prevented from flowing toward the semiconductor film 103a and disappearing.

  By providing the memory element with the above structure, it is possible to easily inject charges from the semiconductor film into the charge storage layer, and it is possible to prevent the charge from being lost from the charge storage layer. That is, when operating as a memory, high-efficiency writing can be performed at a low voltage, and charge retention characteristics can be improved.

(Embodiment 3)
In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device, which is different from that in the above embodiment, will be described with reference to drawings. Specifically, a case where an insulating film containing dispersed particles is used as the charge storage layer will be described.

  First, island-shaped semiconductor films 103a and 103b are formed over a substrate 101 with an insulating film 102 interposed therebetween, and a first insulating film 104 is formed on the surfaces of the semiconductor films 103a and 103b by high-density plasma treatment (FIG. 3). A)). A specific formation method may be performed in the same manner as in FIG.

  Next, an insulating film 106 b (charge storage layer 106 b) having a property of trapping charges is formed so as to cover the insulating film 104. As the insulating film 106b, an insulating film having a defect that traps charges in the film or an insulating film containing conductive particles or semiconductor particles 106a (hereinafter also referred to as dispersed particles 106a) is preferably used. Alternatively, a germanium oxide (GeOx) film, a germanium nitride (GeNx) film, or the like can be used (FIG. 3B). As the charge storage layer 106b including the dispersed particles 106a, for example, an insulating film containing a metal element can be used. Specifically, a metal oxide film, a metal nitride film, a metal oxynitride film, or the like can be used. it can. As the dispersed particles 106a, particles such as germanium (Ge) and a silicon germanium alloy can be included.

For example, as the charge storage layer 106b, an insulating film containing germanium is formed to have a thickness of 1 to 20 nm, preferably 5 to 10 nm, by performing a plasma CVD method in an atmosphere containing a germanium element (for example, GeH ₄ ). Can do. As the insulating film containing germanium, a germanium oxide (GeOx) film, a germanium nitride (GeNx) film, or the like can be formed by performing a plasma CVD method in an atmosphere containing GeH ₄ and oxygen and / or nitrogen. it can.

  An insulating film containing germanium, which is formed of a material mainly containing Si as a semiconductor film and has a defect that traps charges in the film through an insulating film that functions as a tunnel oxide film on the semiconductor film (for example, GeNx ) Or a structure in which a charge storage layer is provided with an insulating film containing germanium particles, carriers injected from the semiconductor film through the insulating film are trapped by defects or germanium particles included in the charge storage layer. Held by.

  After that, by performing the steps shown in FIGS. 1D to 2E, a nonvolatile semiconductor memory device having a memory element can be manufactured (FIG. 3C).

  As shown in this embodiment mode, when the charge storage layer is formed using an insulating film having defects that trap charges in the film or an insulating film containing dispersed particles, the insulating film functioning as a tunnel oxide film has defects. Even in such a case, it is possible to avoid that all charges accumulated in the charge accumulation layer flow out from the defect of the insulating film to the semiconductor film. The charge storage layer formed of a germanium oxide film or nitride film containing dispersed particles has an energy band formed by the dispersed particles as shown in FIG. Therefore, with the use of the structure described in this embodiment, a highly reliable memory element in which data can be easily written and stored charge is not easily lost can be obtained.

(Embodiment 4)
In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device, which is different from that in the above embodiment, will be described with reference to drawings.

  First, island-shaped semiconductor films 103a and 103b are formed over the substrate 101 with the insulating film 102 interposed therebetween, and the insulating film 104, the charge storage layer 106b, and the insulating film 107 are formed so as to cover the island-shaped semiconductor films 103a and 103b. Is formed (FIG. 4A). Note that as a manufacturing method, a method similar to that of FIGS. 1A to 1D described above can be used. In this embodiment mode, the charge storage layer is formed using the charge storage layer described in Embodiment Mode 2, but the charge storage layer 105 described in Embodiment Mode 1 may be formed.

  Next, after the resist 108 is selectively formed so as to cover at least a part of the elements constituting the memory portion, the upper portion of the elements constituting the memory portion and the elements constituting the logic portion which are not covered with the resist 108 are formed. The insulating film 104, the charge storage layer 105, and the insulating film 107 formed above are selectively removed (FIG. 4B). Here, after the resist 108 is selectively formed so as to cover at least part of the insulating film 107 formed above the semiconductor film 103a, the resist 108 is covered by the upper portion of the semiconductor film 103a and the semiconductor film 103b. The insulating film 104, the charge storage layer 105, and the insulating film 107 formed above are selectively removed. As a result, part of the semiconductor film 103a and the surface of the semiconductor film 103b are exposed.

  Next, high-density plasma treatment is performed, and oxidation treatment, nitridation treatment, or oxynitridation treatment is performed (FIG. 4C). As a result, the insulating film 110 is formed on the surface of the insulating film 107, and the insulating film 109 is formed on the exposed surfaces of the semiconductor films 103a and 103b. Here, the insulating film 107 formed of a silicon nitride film or a silicon nitride oxide film is subjected to high-density plasma treatment in an oxygen atmosphere, whereby an oxynitride film (here, a silicon nitride oxide film or a silicon oxide film) is formed on the surface of the insulating film 107. An insulating film 110 having a silicon oxynitride film) is formed. At the same time, an insulating film 109 including a silicon oxide film is formed on the surface of the semiconductor film 103b. Note that the high-density plasma treatment can be performed by using the conditions and methods shown in FIG.

  Next, a conductive film is formed over the semiconductor film 103a and the semiconductor film 103b (FIG. 4D). Here, an example in which the conductive film 111a and the conductive film 111b are stacked is shown as the conductive film. Needless to say, the conductive film may be formed of a single layer or a stacked structure of three or more layers.

  The conductive films 111a and 111b 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 semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus can be used. Here, the conductive film 111a is formed using tantalum nitride, and the conductive film 111b is formed using tungsten in a stacked structure. In addition, tungsten nitride, molybdenum nitride, or titanium nitride can be used as the conductive film 111a, and tantalum, molybdenum, titanium, or the like can be used as the conductive film 111b. The conductive film 111a can be formed by freely combining these materials. In addition, the conductive film 111b can be formed.

  Next, a resist 112 is selectively formed over the conductive film 111b formed over the semiconductor films 103a and 103b, and the insulating film 104 and the charge storage layer provided over the semiconductor film 103a are formed using the resist 112 as a mask. 105, the insulating film 107, the insulating film 110, the conductive film 111a, the conductive film 111b, and the insulating film 109, the conductive film 111a, and the conductive film 111b provided over the semiconductor film 103b are selectively removed (FIG. 5A). )).

  In this embodiment mode, the resist 112 formed above the semiconductor film 103a is a stacked structure of the insulating film 104, the charge storage layer 105, the insulating film 107, and the insulating film 110 formed below the conductive films 111a and 111b. It is formed so as to be approximately the same as or smaller than the width. As a result, does the width of the obtained conductive film 113a substantially match the width of the stacked structure of the insulating film 104, the charge storage layer 105, the insulating film 107, and the insulating film 110 formed below the conductive films 111a and 111b? Or smaller.

  Next, an impurity element is introduced into the semiconductor film 103a and the semiconductor film 103b, whereby the impurity region 114a which functions as a source region or a drain region is separated from the semiconductor film 103a and the semiconductor film 103b. A channel formation region 114b is formed therebetween (FIG. 5B). Note that when the impurity element is introduced into the semiconductor film 103b, the conductive film 113b functioning as a gate electrode is used as a mask so that the impurity region 114a and the channel formation region 114b are formed in the semiconductor film 103b in a self-aligned manner. Can be formed.

  Next, an insulating film is formed over the semiconductor films 103a and 103b and the conductive films 113a and 113b (FIG. 5C). Here, an example is shown in which an insulating film 115a and an insulating film 115b are stacked as the insulating film. Note that the insulating film may be formed with a single layer or a stacked structure of three or more layers. Thereafter, contact holes are selectively formed in the insulating films 115a and 115b to expose the semiconductor films 103a and 103b, and a conductive film 116 is selectively formed so as to fill the contact holes. The conductive film 116 is electrically connected to the impurity regions 114a of the semiconductor films 103a and 103b.

  Note that in the case where the width of the conductive film 113a formed over the semiconductor film 103a is smaller than the width of the stacked structure of the insulating film 104, the charge storage layer 105, the insulating film 107, and the insulating film 110, the semiconductor in FIG. By controlling the conditions for introducing the impurity element into the films 103a and 103b, the low-concentration impurity region 117 into which the impurity element having a lower concentration than the impurity region 114a is introduced can be formed in the semiconductor film 103a (FIG. 6). (A)). The low-concentration impurity region is a semiconductor film 103a located below the insulating film 104 and is a region where the stacked structure of the conductive film 113a and the insulating film 104, the charge storage layer 105, the insulating film 107, and the insulating film 110 does not overlap. It is formed in a semiconductor film 103a located below (a region where the channel formation region 114b and the conductive film 113a do not overlap).

  After that, by forming the insulating films 115a and 115b and the conductive film 116 as in FIG. 5C, a nonvolatile semiconductor memory device having a memory element can be obtained (FIG. 6B).

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 5)
In this embodiment, a method for manufacturing a semiconductor device in which formation of an insulating film, a conductive film, or a semiconductor film and plasma treatment are sequentially performed in a manufacturing process of a nonvolatile semiconductor memory device will be described with reference to drawings.

  In the case where an insulating film, a conductive film, or a semiconductor film is continuously formed and plasma treatment is performed, an apparatus including a plurality of chambers can be used. An example of an apparatus provided with a plurality of chambers is shown in FIG. Note that FIG. 7A is a top view of a structural example of the apparatus (continuous film formation system) described in this embodiment.

  The apparatus shown in FIG. 7A includes a first chamber 311, a second chamber 312, a third chamber 313, a fourth chamber 314, load lock chambers 310 and 315, and a common chamber 320. Each chamber is airtight. Each chamber is provided with a vacuum exhaust pump and an inert gas introduction system.

  The load lock chambers 310 and 315 are rooms for carrying samples (processing substrates) into the system. The first to fourth chambers are chambers for forming a conductive film, an insulating film, or a semiconductor film on the substrate 101, etching, plasma treatment, and the like. The common chamber 320 is disposed in common for the load lock chambers 310 and 315 and the first to fourth chambers. Gate valves 322 to 327 are provided between the common chamber 320, the load lock chambers 310 and 315, and the first to fourth chambers 311 to 314. Note that a robot arm 321 is provided in the common chamber 320, and the substrate 101 is carried to each room by the robot arm 321.

  Hereinafter, as a specific example, a semiconductor film is oxidized with respect to the substrate 101 in the first chamber 311 by plasma treatment, nitrided by using plasma treatment in the second chamber 312, and charge accumulation in the third chamber 313. An example in which a layer is formed and an insulating film is formed in the fourth chamber 314 is described.

  First, the substrate 101 is carried into the load lock chamber 310 together with a cassette 328 containing a plurality of substrates. After loading the cassette 328, the loading door of the load lock chamber 310 is closed. In this state, the gate valve 322 is opened, one processing substrate is taken out from the cassette 328, and placed in the common chamber 320 by the robot arm 321. At this time, the alignment of the substrate 101 is performed in the common chamber 320.

  Next, the gate valve 322 is closed, and then the gate valve 324 is opened. Then, the substrate 101 over which the island-shaped semiconductor film is formed is transferred to the first chamber 311. A first high-density plasma treatment is performed in the first chamber 311. Here, high-density plasma treatment is performed in an oxygen atmosphere in the first chamber 311 to form an oxide film on the surface of the semiconductor film. Note that the high-density plasma treatment may be performed using the conditions described in Embodiment Mode 1.

  Next, the substrate 101 is pulled out to the common chamber 320 by the robot arm 321 and transferred to the second chamber 312. In the second chamber 312, the second high-density plasma treatment is performed. Here, high-density plasma treatment is performed in a nitrogen atmosphere to nitride the oxide film formed on the surface of the semiconductor film.

  Next, the substrate 101 is pulled out to the common chamber 320 by the robot arm 321 and transferred to the third chamber 313. In the third chamber 313, a charge storage layer is formed by plasma CVD. The charge storage layer may be formed using the material described in Embodiment Mode 1 or 2. Here, a film containing germanium is formed by a plasma CVD method. Note that although an example in which the plasma CVD method is used is shown here, the sputtering method using a target may be used.

  Next, the substrate 101 is pulled out to the common chamber 320 by the robot arm 321 and transferred to the fourth chamber 314. In the fourth chamber 314, an insulating film is formed by a plasma CVD method. For example, an insulating film containing nitrogen is formed by a plasma CVD method.

  Then, the substrate 101 is transferred to the load lock chamber 315 by the robot arm 321 and stored in the cassette 329.

  Note that FIG. 7A is just an example, and the number of chambers can be increased. 7A shows an example in which single-type chambers are used as the first to fourth chambers 311 to 314, but a configuration may be adopted in which a plurality of sheets are processed at once using a batch-type chamber. .

  In this manner, by using the apparatus described in this embodiment mode, a conductive film, an insulating film, or a semiconductor film can be continuously formed and high-density plasma treatment can be performed without being exposed to the atmosphere. . Therefore, it is possible to prevent contamination from being mixed and improve production efficiency.

  Next, an example of an apparatus for performing high-density plasma treatment in the present invention will be described with reference to FIG.

  The apparatus shown in FIG. 7B includes a support base 351 for placing an object to be processed 331 for performing high-density plasma treatment, a gas supply portion 352 for introducing gas, an exhaust port 353, an antenna 354, And a dielectric plate 355 and a high-frequency supply unit 356 that supplies a high-frequency for generating high-density plasma. In addition, the temperature of the object to be processed 331 can be controlled by providing the support base 351 with the temperature controller 357. Hereinafter, an example of high-density plasma processing will be described. In addition, as a to-be-processed object, what can perform plasma processing in the said embodiment can be used.

First, the processing chamber is evacuated and a gas containing oxygen or nitrogen is introduced from the gas supply portion 352. For example, as the gas containing oxygen, oxygen (O ₂ ) and a rare gas or a mixed gas of oxygen, hydrogen, and a rare gas can be introduced. As the gas containing nitrogen, a mixed gas of nitrogen and a rare gas or NH ₃ and a rare gas can be introduced. Next, the object to be processed 331 is placed on the support base 351 having the temperature control unit 357, and the object to be processed 331 is heated to 100 ° C to 550 ° C. Note that the distance between the workpiece 331 and the dielectric plate 355 is in the range of 20 to 80 mm (preferably 20 to 60 mm).

Next, microwaves are supplied from the high-frequency supply unit 356 to the antenna 354. Here, microwaves with a frequency of 2.45 GHz are supplied. Then, by introducing a microwave from the antenna 354 into the processing chamber through the dielectric plate 355, a high-density plasma 358 activated by plasma excitation is generated. For example, when plasma treatment is performed in an NH ₃ gas and Ar gas atmosphere, high-density excitation plasma in which NH ₃ gas and Ar gas are mixed by a microwave is generated. In a high-density excitation plasma in which NH ₃ gas and Ar gas are mixed, Ar gas is excited by the introduced microwave to generate radicals (Ar ·), and the Ar radicals collide with NH ₃ molecules. As a result, radicals (NH.) Are generated. The NH · and the object to be processed 331 react to perform nitridation of the object to be processed 331. Thereafter, NH ₃ gas and Ar gas are exhausted from the exhaust port 353 to the outside of the processing chamber.

Thus, by performing plasma treatment using the apparatus shown in FIG. 7B, a low electron temperature (1.5 eV or less) and a high electron density (1 × 10 ¹¹ cm ⁻³ or more) are obtained. It is possible to form an object to be processed with very little plasma damage.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 6)
In this embodiment, a method for manufacturing a nonvolatile semiconductor memory device, which is different from that in the above embodiment, will be described with reference to drawings. Specifically, a case where gate insulating films of a plurality of transistors provided in a logic portion are formed with different thicknesses in a semiconductor device having a memory portion and a logic portion will be described.

  In the case where a plurality of functional circuits are provided using a plurality of thin film transistors in the logic portion, characteristics required for each circuit are different. Therefore, it is preferable that gate insulating films of the thin film transistors provided in the respective functional circuits are formed with different thicknesses. There is a case. 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. For example, for a circuit with a low driving voltage and a small threshold voltage variation, an insulating film with a small film thickness formed by the high-density plasma treatment described in the above embodiment is applied, and a gate with a large driving voltage is applied. An insulating film having a large film thickness is applied to a circuit that requires the pressure resistance of the insulating film. Hereinafter, description will be given with reference to the drawings.

  First, island-shaped semiconductor films 103a to 103c are formed over the substrate 101 with the insulating film 102 interposed therebetween (FIG. 9A). Here, the semiconductor film 103a forms an element of a memory portion, and the semiconductor films 103b and 103c form an element of a logic portion.

  The semiconductor films 103a and 103b are preferably formed using a crystalline semiconductor film. The crystalline semiconductor film is obtained by crystallizing an amorphous semiconductor film formed over the insulating film 102 by heat treatment or laser light irradiation, or after amorphizing the crystalline semiconductor film formed over the insulating film 102. , Recrystallized materials, and the like.

When crystallization or recrystallization is performed by laser light irradiation, an LD-excited continuous wave (CW) laser (YVO ₄ , second harmonic (wavelength 532 nm)) can be used as a laser light source. 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 film is irradiated with CW laser light, energy is continuously given to the semiconductor film. Therefore, once the semiconductor film is in a molten state, the molten state can be continued. Furthermore, the solid-liquid interface of the semiconductor film can be moved by scanning with CW laser light, 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 film can always remain in a molten state if the laser pulse interval is shorter than the time from when the semiconductor film melts until it solidifies. A semiconductor film 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.

  Next, the insulating film 104, the charge storage layer 105, and the insulating film 107 are formed over the semiconductor films 103a to 103c (FIG. 9B).

  The insulating film 104 is formed with a thickness of 1 to 10 nm, preferably 5 to 10 nm, by performing oxidation treatment or nitridation treatment on the semiconductor films 103a to 103c using high-density plasma treatment. Here, a material containing Si as a main component is used for the semiconductor films 103a to 103c, and oxidation treatment is performed by high-density plasma treatment to form silicon oxide films on the surfaces of the semiconductor films 103a to 103c, and then high-density plasma treatment. An oxynitride film is formed on the surface of the silicon oxide film by performing a nitriding process.

The charge storage layer 105 is provided by being formed over the insulating film 104. As the charge storage layer 105, a material having an energy gap (band gap) smaller than that of the substance used for the semiconductor films 103a and 103b is preferably used. Here, as the charge storage layer 105, a film containing germanium as a main component is formed with a thickness of 1 to 20 nm, preferably 5 to 10 nm, by performing plasma CVD in an atmosphere containing GeH ₄ . Note that the charge storage layer 105 may be formed using the charge storage layer described in Embodiment Mode 3.

  A material containing Si as a main component is used as the semiconductor films 103a to 103c, and a film containing germanium having a smaller energy gap than Si is formed on the semiconductor films 103a to 103c through the insulating film 104 functioning as a tunnel oxide film. 105, the second barrier formed by the insulating film 104 against the charge of the charge storage layer 105 becomes higher in energy than the first barrier formed by the insulating film 104 against the charge of the semiconductor film 103a. . As a result, charge can be easily injected from the semiconductor film 103a into the charge storage layer 105, and the charge can be prevented from disappearing from the charge storage layer 105. That is, when operating as a memory, high-efficiency writing can be performed at a low voltage, and charge retention characteristics can be improved.

  The insulating film 107 is provided by forming a silicon oxynitride film, a silicon nitride film, a silicon nitride oxide film, or the like over the charge storage layer 105. Here, a silicon nitride film or a silicon nitride oxide film is formed as the insulating film 107 with a thickness of 1 to 20 nm, preferably 5 to 10 nm, by a plasma CVD method. Further, the charge storage layer 105 is subjected to high-density plasma treatment in a nitrogen atmosphere, and the surface of the charge storage layer 105 is nitrided to use a nitride film (eg, a film containing germanium as a main component as the charge storage layer 105). In this case, GeNx) may be formed. In this case, a nitride film obtained by nitriding treatment may be used as the insulating film 107, or the insulating film described above may be separately formed as the insulating film 107 on the nitride film obtained by nitriding treatment. In addition, the insulating film 107 may be formed using aluminum oxide (AlOx), hafnium oxide (HfOx), or tantalum oxide (TaOx).

  Next, after a resist 108 is selectively formed so as to cover the elements constituting the memory portion, the insulating film 104, the charge storage layer 105, and the insulating film 107 formed above the elements constituting the logic portion are selectively formed. (FIG. 9C). Here, after the resist 108 is selectively formed so as to cover the insulating film 107 formed over the semiconductor film 103a, the insulating film 104, the charge storage layer 105, and the insulating film formed over the semiconductor films 103b and 103c. The film 107 is removed, and the semiconductor films 103b and 103c are selectively exposed.

  Next, high-density plasma treatment is performed, and oxidation treatment, nitridation treatment, or oxynitridation treatment is performed (FIG. 10A). As a result, the insulating film 110 is formed on the surface of the insulating film 107 formed above the semiconductor film 103a, and the insulating film 109 is formed on the surfaces of the semiconductor films 103b and 103c. Here, the insulating film 107 formed of a silicon nitride film or a silicon nitride oxide film is subjected to high-density plasma treatment in an oxygen atmosphere, whereby an oxynitride film (here, a silicon nitride oxide film or a silicon oxide film) is formed on the surface of the insulating film 107. An insulating film 110 having a silicon oxynitride film) is formed. At the same time, an insulating film 109 including a silicon oxide film is formed on the surface of the semiconductor film 103b.

  Next, a conductive film is formed over the semiconductor films 103a to 103c, a resist 112 is selectively formed over the conductive films located over the semiconductor films 103a and 103b, and the conductive film is selectively etched. Thus, the conductive films 113a and 113b are formed over the semiconductor films 103a and 103b, and the conductive film formed over the semiconductor film 103c is removed (FIG. 10B). For the conductive films 113a and 113b, the materials used for the conductive films 111a and 111b described in the above embodiment can be used.

  Next, the insulating film 121 is formed so as to cover the exposed surfaces of the semiconductor films 103a to 103c and the conductive films 113a and 113b, and then the conductive film 122 is formed over the insulating film 121 (FIG. 10C). The insulating film 121 functions as a gate insulating film of a thin film transistor including the semiconductor film 103c.

  Next, a resist 123 is selectively formed over the conductive film 122 formed over the semiconductor film 103c, and the conductive film 122 and the insulating film 121 are selectively removed using the resist 123 as a mask (FIG. A)).

  Next, by introducing an impurity element into the semiconductor films 103a to 103c, a channel is formed between the impurity regions 114a that can function as a source region or a drain region in the semiconductor films 103a to 103c and the impurity regions 114a that are provided apart from each other. A region 114b is formed (FIG. 11B). Note that when the impurity element is introduced into the semiconductor films 103a to 103c, the conductive regions 113a, 113b, and 124 functioning as gate electrodes are used as masks, so that the impurity region 114a and the channel formation region are self-aligned. 114b can be formed.

  Next, an insulating film is formed over the conductive films 113a, 113b, and 124 and the exposed semiconductor films 103a to 103c (FIG. 11C). Here, an example is shown in which an insulating film 115a and an insulating film 115b are stacked as the insulating film. Note that the insulating film may be formed with a single layer or a stacked structure of three or more layers. Thereafter, contact holes are selectively formed in the insulating films 115a and 115b to expose the semiconductor films 103a to 103c, and a conductive film 116 is selectively formed so as to fill the contact holes. The conductive film 116 is electrically connected to the impurity regions 114a of the semiconductor films 103a to 103c.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 7)
In this embodiment, application examples of a semiconductor device including the nonvolatile semiconductor memory device described in the above embodiment and capable of inputting and outputting data without contact will be described below with reference to 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.

  First, an example of the top structure of the semiconductor device described in this embodiment is described with reference to FIG. A semiconductor device 80 illustrated in FIG. 12A includes a thin film integrated circuit 131 provided with a plurality of elements included in a memory portion and a logic portion, and a conductive film 132 functioning as an antenna. The conductive film 132 functioning as an antenna is electrically connected to the thin film integrated circuit 131. Note that although an example in which the conductive film 132 functioning as an antenna is provided in a coil shape and an electromagnetic induction method or an electromagnetic coupling method is applied is described in this embodiment mode, the semiconductor device of the present invention is not limited thereto, and a microwave method is used. It is also possible to apply. In the case of a microwave method, the shape of the conductive film 132 functioning as an antenna may be determined as appropriate depending on the wavelength of the electromagnetic wave used.

  FIG. 12B is a schematic view of the cross section of FIG. The conductive film 132 functioning as an antenna may be provided above the elements included in the memory portion and the logic portion. For example, in the structure described in the above embodiment mode, the antenna is provided over the insulating film 115b with the insulating film 133 interposed therebetween. The conductive film 132 functioning as can be provided.

  Next, operation of the semiconductor device described in this embodiment is described.

  The semiconductor device 80 has a function of communicating data without contact, and controls the high frequency circuit 81, the power supply circuit 82, the reset circuit 83, the clock generation circuit 84, the data demodulation circuit 85, the data modulation circuit 86, and other circuits. A control circuit 87, a memory circuit 88, and an antenna 89 are provided (FIG. 13A). The high frequency circuit 81 is a circuit that receives a signal from the antenna 89 and outputs the signal received from the data modulation circuit 86 from the antenna 89, and the power circuit 82 is a circuit that generates a power supply potential from the received signal, and a reset circuit 83. Is a circuit that generates a reset signal, a clock generation circuit 84 is a circuit that generates various clock signals based on the reception signal input from the antenna 89, and a data demodulation circuit 85 demodulates the reception signal to control the control circuit 87. The data modulation circuit 86 is a circuit that modulates the signal received from the control circuit 87. Further, as the control circuit 87, for example, a code extraction circuit 91, a code determination circuit 92, a CRC determination circuit 93, and an output unit circuit 94 are provided. The code extraction circuit 91 is a circuit that extracts a plurality of codes included in an instruction sent to the control circuit 87, and the code determination circuit 92 compares the extracted code with a code corresponding to a reference. The CRC determination circuit 93 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 89. The radio signal is sent to the power supply circuit 82 via the high frequency circuit 81, and a high power supply potential (hereinafter referred to as VDD) is generated. VDD is supplied to each circuit included in the semiconductor device 80. The signal sent to the data demodulation circuit 85 via the high frequency circuit 81 is demodulated (hereinafter, demodulated signal). Further, the signal and the demodulated signal that have passed through the reset circuit 83 and the clock generation circuit 84 via the high frequency circuit 81 are sent to the control circuit 87. The signal sent to the control circuit 87 is analyzed by the code extraction circuit 91, the code determination circuit 92, the CRC determination circuit 93, and the like. Then, information on the semiconductor device stored in the memory circuit 88 is output in accordance with the analyzed signal. The output semiconductor device information is encoded through the output unit circuit 94. Further, the encoded information of the semiconductor device 80 passes through the data modulation circuit 86 and is transmitted as a radio signal by the antenna 89. Note that in a plurality of circuits included in the semiconductor device 80, a low power supply potential (hereinafter referred to as VSS) is common and VSS can be GND.

  As described above, by transmitting a signal from the reader / writer to the semiconductor device 80 and receiving the signal transmitted from the semiconductor device 80 by the reader / writer, the data of the semiconductor device can be read.

  Further, the semiconductor device 80 may be of a type in which power supply voltage is supplied to each circuit by electromagnetic waves without mounting a power source (battery), or each circuit is mounted by using electromagnetic waves and a power source (battery). It is good also as a type which supplies a power supply voltage to.

  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 a side surface of the portable terminal including the display portion 3210, and a semiconductor device 3230 is provided on a side surface of the article 3220 (FIG. 13B). 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 a belt conveyor, the product 3260 can be inspected using the reader / writer 3240 and the semiconductor device 3250 provided in the product 3260 (FIG. 13C). 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 to the above, the application of the semiconductor device provided with the nonvolatile semiconductor memory device of the present invention is wide-ranging, so long as it is a product that clarifies information such as the history of the object in a non-contact manner and is useful for production and management. It can be applied to anything. For example, banknotes, coins, securities, certificate documents, bearer bonds, packaging containers, books, recording media, personal belongings, vehicles, foods, clothing, health supplies, daily necessities, chemicals, etc. It can be provided and used in an electronic device or the like. These examples will be described with reference to FIG.

  Banknotes and coins are money that circulates in the market, and include those that are used in the same way as money in a specific area (cash vouchers), commemorative coins, and the like. Securities refer to checks, securities, promissory notes, etc. (FIG. 14A). Certificates refer to driver's licenses, resident's cards, etc. (FIG. 14B). Bearer bonds refer to stamps, gift tickets, various gift certificates, etc. (FIG. 14C). Packaging containers refer to wrapping paper for lunch boxes, plastic bottles, and the like (FIG. 14D). Books refer to books, books, and the like (FIG. 14E). The recording media refer to DVD software, video tapes, and the like (FIG. 14F). The vehicles refer to vehicles such as bicycles, ships, and the like (FIG. 14G). Personal belongings refer to bags, glasses, and the like (FIG. 14H). Foods refer to food products, beverages, and the like. Clothing refers to clothing, footwear, and the like. Health supplies refer to medical equipment, health equipment, and the like. Livingware refers to furniture, lighting equipment, and the like. Chemicals refer to pharmaceuticals, agricultural chemicals, and the like. Electronic devices refer to liquid crystal display devices, EL display devices, television devices (television receivers, thin television receivers), cellular phones, and the like.

  Forgery can be prevented by providing the semiconductor device 80 on bills, coins, securities, certificates, bearer bonds, and the like. In addition, by providing semiconductor devices 80 in personal items such as packaging containers, books, recording media, personal items, foods, daily necessities, electronic devices, etc., the efficiency of inspection systems and rental store systems will be improved. Can do. By providing the semiconductor device 80 in vehicles, health supplies, medicines, etc., it is possible to prevent counterfeiting and theft, and in the case of medicines, it is possible to prevent mistakes in taking medicines. As a method of providing the semiconductor device 80, the semiconductor device 80 is provided by being attached to the surface of the article or embedded in the article. For example, a book may be embedded in paper, and a package made of an organic resin may be embedded in the organic resin.

  In this way, by providing semiconductor devices in packaging containers, books, recording media, personal items, foods, clothing, daily necessities, electronic devices, etc., the efficiency of inspection systems and rental store systems is improved. be able to. Further, forgery or theft can be prevented by providing a semiconductor device in the vehicles. Moreover, by embedding it in creatures such as animals, it is possible to easily identify individual creatures. For example, by embedding a semiconductor device equipped with a sensor in a living creature such as livestock, it is possible to easily manage the health state such as the current body temperature as well as the year of birth, gender or type.

  As described above, the applicable range of the semiconductor device of the present invention is so wide that the semiconductor device can be used for electronic devices in various fields. Note that this embodiment mode can be freely combined with the above embodiment modes.

8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. FIG. 11 illustrates an example of a device for manufacturing a nonvolatile semiconductor memory device of the present invention. 1 is a diagram showing an example of a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 8A and 8B illustrate an example of a method for manufacturing a nonvolatile semiconductor memory device of the present invention. 1 is a diagram showing an example of a nonvolatile semiconductor memory device of the present invention. FIG. 11 shows an example of a usage pattern of a nonvolatile semiconductor memory device of the present invention. FIG. 11 shows an example of a usage pattern of a nonvolatile semiconductor memory device of the present invention. 6A and 6B illustrate a charge transfer of the nonvolatile semiconductor memory device of the present invention. 1 is a diagram illustrating an example of a conventional nonvolatile semiconductor memory device.

Explanation of symbols

80 Semiconductor Device 81 High Frequency Circuit 82 Power Supply Circuit 83 Reset Circuit 84 Clock Generation Circuit 85 Data Demodulation Circuit 86 Data Modulation Circuit 87 Control Circuit 88 Memory Circuit 89 Antenna 91 Code Extraction Circuit 92 Code Determination Circuit 93 CRC Determination Circuit 94 Output Unit Circuit 101 Substrate 102 Insulating film 104 Insulating film 105 Charge storage layer 107 Insulating film 108 Resist 109 Insulating film 110 Insulating film 112 Resist 116 Conductive film 117 Low concentration impurity region 121 Insulating film 122 Conductive film 123 Resist 131 Thin film integrated circuit 132 Conductive film 133 Insulating film 301 Single crystal semiconductor substrate 302 p well 303 field oxide film 304 gate insulating film 310 load lock chamber 311 chamber 312 chamber 313 chamber 314 chamber 315 load lock chamber 320 Chamber 321 Robot arm 322 Gate valve 324 Gate valve 328 Cassette 329 Cassette 331 Processed object 351 Support base 352 Gas supply unit 353 Exhaust port 354 Antenna 355 Dielectric plate 356 High frequency supply unit 357 Temperature control unit 358 High density plasma 402 Insulating film 800 Semiconductor Film 801 Insulating film 802 Charge storage layer 803 Insulating film 804 Control gate electrode 805 Source 806 Drain 103a Semiconductor film 103b Semiconductor film 103c Semiconductor film 106a Semiconductor particles 106a Dispersed particles 106b Charge storage layer 106b Insulating film 111a Conductive film 111b Conductive film 113a Conductive film 113b Conductive film 114a Impurity region 114b Channel formation region 115a Insulating film 115b Insulating film 3200 Reader / writer 3210 Display unit 3220 Product 3230 Semiconductor device 3240 Reader / Writer 3250 Semiconductor Device 3260

Claims (5)

Forming a first semiconductor film and a second semiconductor film on a substrate;
After performing the first high-density plasma treatment in an oxygen atmosphere, and subsequently performing a second high-density plasma treatment in a nitrogen atmosphere, the surface of the first semiconductor film and the second semiconductor film Forming a first insulating film on the surface;
Forming a charge storage layer having a material having an energy gap smaller than that of the first semiconductor film and the second semiconductor film on the first insulating film;
Forming a second insulating film containing nitrogen on the charge storage layer;
Selectively removing the first insulating film, the charge storage layer, and the second insulating film formed on the second semiconductor film to expose a surface of the second semiconductor film;
By performing a third high-density plasma treatment in an oxygen atmosphere, the surface of the second insulating film containing nitrogen formed above the first semiconductor film is oxidized, and at the same time, the second semiconductor film Forming a gate insulating film on the surface of
Forming a conductive film on the second insulating film and the gate insulating film whose surfaces are oxidized;
By selectively removing the first insulating film, the charge storage layer, the second insulating film, the gate insulating film, and the conductive film, the first insulating film overlaps at least a part of the first semiconductor film. The first insulating film, the charge storage layer, the second insulating film, and the conductive film are left, and the gate insulating film and the conductive film are left so as to overlap with at least part of the second semiconductor film. A method for manufacturing a nonvolatile semiconductor memory device. Oite to claim 1,
The method for manufacturing a nonvolatile semiconductor memory device, wherein the first high-density plasma treatment and the second high-density plasma treatment are continuously performed without exposing the semiconductor film to the atmosphere. In claim 1 or claim 2 ,
The method for manufacturing a nonvolatile semiconductor memory device, wherein the charge storage layer and the second insulating film are formed continuously without being exposed to the atmosphere. In any one of Claims 1 thru | or 3 ,
The method of manufacturing a nonvolatile semiconductor memory device, wherein the charge storage layer is formed of a film containing germanium as a main component. In any one of Claims 1 thru | or 4 ,
The method for manufacturing a nonvolatile semiconductor memory device, wherein the conductive film is formed using a conductive film containing nitrogen atoms.

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