JP3917310B2 - Method for forming solid of ferroelectric or high dielectric constant material and method for manufacturing semiconductor device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an inorganic compound solid represented by a ferroelectric thin film used in a semiconductor device such as a ferroelectric memory.
[0002]
[Prior art]
A ferroelectric memory is a non-volatile memory device using a ferroelectric film as a capacitor for holding electric charge, and is excellent in high speed, low power consumption, high integration, and rewriting resistance. When polarization is generated by applying an electric field to the ferroelectric film, the polarization is maintained even after the electric field is removed. Thereby, a nonvolatile storage function is realized.
[0003]
FIG. 13 is a cross-sectional view showing the cell structure of the ferroelectric memory. Impurity diffusion layers 3 and 4 are formed at an interval in the element formation region separated by the field oxide film 2 on the surface of the semiconductor substrate 1, and the semiconductor substrate 1 between these impurity diffusion layers 3 and 4 is formed. On the surface, a gate electrode 6 is formed with a gate insulating film 5 interposed. In this way, the transistor TR is formed.
[0004]
The gate electrode 6 is covered with a first interlayer insulating film 7, and a capacitor structure C is formed on the first interlayer insulating film 7 by sandwiching the ferroelectric film 10 between the lower electrode 11 and the upper electrode 12. Is provided.
The upper electrode 12 is covered with the second interlayer insulating film 8. The first aluminum wiring 9 formed on the second interlayer insulating film 8 is joined to the upper electrode 12 and the impurity diffusion layer 4 through the contact holes 14 and 15, and the upper electrode 12 and the impurity diffusion layer are joined. 4 is electrically connected.
[0005]
In the ferroelectric memory having the cell structure, the impurity diffusion layer 3 forms a bit line, the gate electrode 6 forms a word line, and the lower electrode 11 forms a plate line. Therefore, an appropriate write voltage is applied between the bit line (impurity diffusion layer 3) and the plate line (lower electrode 11), and a selection voltage is applied to the word line (gate electrode 6) to make the transistor TR conductive. An electric field can be applied to the ferroelectric film 10. Thereby, the ferroelectric film 10 can be polarized according to the direction and strength of the applied electric field.
[0006]
At the time of reading, an appropriate selection voltage is applied to the word line (gate electrode 6) to make the transistor TR conductive, and an appropriate reading voltage is applied to the plate line (lower electrode 11). At this time, the potential appearing on the bit line (impurity diffusion layer 3) is one of two different potentials depending on the direction of polarization of the ferroelectric film 10. Based on this, it can be checked whether this cell is in the “1” state or the “0” state.
[0007]
As shown in FIG. 13, when a multilayer wiring is necessary, the first aluminum wiring 9 is further covered with a third interlayer insulating film 16. A second aluminum wiring 17 is further formed on the third interlayer insulating film 16, and the second aluminum wiring 17 is connected to the first aluminum wiring 9 through the contact hole 18. The second aluminum wiring 17 is further covered with a protective film 19.
[0008]
Ferroelectric film materials include PZT (Pb (Zr, Ti) O_Three) Series and SBT (SrBi₂Ta₂O₉In general, complex oxide ferroelectrics typified by) are used. These thin films are formed by, for example, a sol-gel method. The sol-gel method is a method in which a liquid (sol) raw material is coated on a substrate and fired by heat treatment to obtain a required film. In the sol-gel method of PZT, for example, Pb (CH, which is an organic compound containing a metal element, is used as a starting material._ThreeCOO)₂・ 3H₂O, Zr (n-OC_FourH₉)_Four, Ti (i-OC_ThreeH₇)_FourA solution using 2-methoxyethanol as a solvent is used. This organic compound solution is applied onto a substrate by spin coating, dried at 150 ° C. to 180 ° C., and then pre-baked at 400 ° C. for 30 minutes in a dry air atmosphere. This process is repeated until a predetermined film thickness is obtained, and finally, heat treatment is performed at 600 ° C. to 700 ° C. to crystallize the entire film.
[0009]
[Problems to be solved by the invention]
However, the crystallization process at such a high temperature deteriorates the element characteristics of the transistor TR formed before that, and each film at the interface between the ferroelectric film 10 and the upper and lower electrodes 11 and 12. Due to the interdiffusion of materials, the characteristics of the ferroelectric film 10 itself are also deteriorated. For this reason, a ferroelectric memory having good characteristics cannot always be realized.
[0010]
The reason why the high temperature crystallization treatment as described above is necessary is that organic substances remain in the film before the crystallization treatment. Although a certain amount of organic substances can be removed by pre-baking at a temperature of about 400 ° C., heat treatment at a temperature exceeding 700 ° C. is necessary to sufficiently remove the organic substances in the film. However, at such a high temperature, crystallization of the film material starts, so that the purpose of temporary baking is lost and damage to the transistor TR formed on the semiconductor substrate 1 also increases.
[0011]
Therefore, conventionally, there is no method for forming a ferroelectric film that is well crystallized by a low-temperature heat treatment. For this reason, a ferroelectric memory having good characteristics cannot be provided.
Accordingly, an object of the present invention is to solve the above technical problem and to use an organic compound material containing a metal element.Of ferroelectric or high dielectric constant materialsWhen forming solids, better heat treatment at relatively low temperaturesOf ferroelectric or high dielectric constant materialsIt is to provide a method by which a solid can be formed.
[0012]
Another object of the present invention is to provide a method for manufacturing a semiconductor device, which can form a good functional thin film on a semiconductor substrate by heat treatment at a relatively low temperature, thereby realizing a semiconductor device with good characteristics. It is to be.
[0013]
[Means for Solving the Problems and Effects of the Invention]
  In order to achieve the above object, an invention according to claim 1 is a method of firing an organic compound containing a metal element to form a solid of a ferroelectric material or a high dielectric constant material, wherein the organic compound contains a metal element. A process of forming a film by applying a solution of a compound material on a substrate, and thereafter performing an organic substance removal process on the organic compound material containing the metal element to remove the organic substance in the film, thereby removing the organic substance as an inorganic compound material A step of crystallizing the inorganic compound material obtained by the organic substance removal step by calcination to obtain a solid of a ferroelectric or high dielectric constant material. In the organic substance removal step, the organic compound material The organic compound material is heated to a temperature at which crystallization does not occur while the organic matter remains, and is maintained at that temperature by rapid thermal annealing together with the pressure reducing step of placing the substrate in a reduced pressure atmosphere. Heat treatment is performed in parallel toThe crystallization step is performed after the decompression step.This is a method for forming a solid of a ferroelectric or high dielectric constant material.
[0014]
  According to this method, the organic compound material is placed in a reduced-pressure atmosphere,With rapid thermal annealing, the temperature is raised to a temperature at which crystallization does not occur while organic matter remains, and is maintained at that temperature.By performing the heat treatment in parallel, an organic substance that becomes a crystallization inhibiting factor can be sufficiently removed. Further, since firing for crystallization is performed, the inorganic compound material can be crystallized by firing at a relatively low temperature to obtain the solid. This can prevent the material from diffusing between other solids adjacent to the inorganic compound solid, and if there are other solid parts integrated with the inorganic compound solid, Thermal effects can be suppressed.
[0015]
That is, the crystallization step is preferably performed at a temperature lower than the temperature at which material diffusion occurs between other solids adjacent to the inorganic compound solid. Similarly, it is preferable that the crystallization step is performed at a temperature equal to or lower than a predetermined temperature determined so as to prevent thermal influence on other solid portions integrated with the inorganic compound solid.
[0016]
the aboveThe heat treatment is preferably performed at a temperature lower than the temperature at which the material diffuses between other solids adjacent to the organic compound material. Similarly, it is preferably performed at a temperature equal to or lower than a predetermined temperature so as to prevent a thermal influence on other solid parts to be treated together with the organic compound material.
[0017]
  Moreover, according to the method of Claim 1, volatilization of organic matter is promoted by placing the organic compound material in a reduced-pressure atmosphere. Thereby, an organic substance can be removed efficiently..
[0018]
  For example, the organic substance removing step including the pressure reducing step and the crystallization step may be performed by different processing apparatuses. That is, for example, the organic substance removing step may be performed by a lamp heating apparatus with a reduced pressure in the processing chamber, and the crystallization step may be performed using a heating furnace.
  BookinventionThenSince the crystallization step is performed after the organic substance in the organic compound material is surely removed by the decompression step, the crystallization of the inorganic compound material can be favorably progressed at a low temperature.
[0023]
  The organic substance removal treatment can also be performed by applying energy to the organic compound material by electromagnetic waves such as ultraviolet rays and microwaves, or active particles such as plasma.
  Claim2The described invention is a method of firing an organic compound containing a metal element to form a solid of a ferroelectric or high dielectric constant material, wherein a solution of the organic compound material containing the metal element is applied onto a substrate. A step of forming a film, and thereafter, an organic compound material containing a metal element is subjected to an organic substance removal treatment to remove the organic substance in the film, thereby forming an inorganic compound material, and an inorganic substance obtained by the organic substance removal step And a crystallization step of crystallizing the compound material by calcination to obtain a solid of a ferroelectric or high dielectric constant material, and in the organic substance removal step, the organic compound material is treated with activated oxygen particles, A method of forming a solid of a ferroelectric or high dielectric constant material, wherein the heat treatment at a temperature at which crystallization of the organic compound material does not occur is performed in parallel.
[0024]
  As the activated oxygen particles, ozone (O_Three), Oxygen radicals, oxygen ions (O⁺⁺, O⁺).
  Claim3The invention described in the above item is characterized in that the activated oxygen particles are oxygen radicals.2A method of forming a solid of the described ferroelectric or high dielectric constant material.
  When the organic compound material is brought into contact with the activated oxygen particles, energy can be imparted to the organic matter in the material, thereby achieving an organic matter removal treatment.
  In addition, it is preferable that the heat processing with respect to an organic compound material is performed at the temperature which does not produce mutual diffusion of the material between other adjacent solids. Furthermore, when the said inorganic compound solid is integrated with another solid part, it is preferable to carry out at the temperature which can minimize the heat influence given to the solid part.
  Claim4The invention described in claim 1, wherein the step of forming the film includes a step of pre-baking after drying the solution applied to the substrate.3Or a solid forming method of the ferroelectric or high dielectric constant material according to any one of the above.
[0025]
As the ferroelectric, for example, PZT (Pb (Zr, Ti) O_Three) And SBT (SrBi₂Ta₂O₉) Can be exemplified.
thisinventionTherefore, a ferroelectric solid can be formed by low-temperature heat treatment.
[0026]
  Claim5The invention described in claim 1 is provided on the semiconductor substrate.4A method of manufacturing a semiconductor device, comprising a step of forming a functional thin film made of a ferroelectric or a high dielectric constant solid by the method described in any one of the above.
  The functional thin film may be a capacitor film, and the capacitor film may be made of a ferroelectric.
[0027]
According to the present invention, the functional thin film can be formed by a process at a relatively low temperature, so that it is possible to prevent the mutual diffusion of the material between the films and the thermal effect on the functional element formed on the semiconductor substrate. Thus, a semiconductor device with good characteristics can be realized.
That is, the functional thin film formation process does not cause material diffusion at the film interface, and does not deteriorate the characteristics of the functional element when the functional element is formed on the semiconductor substrate. It is preferably performed at temperature.
[0028]
  Claim6The described invention includes an element forming step for forming a functional element on the semiconductor substrate before the step of forming the functional thin film.5It is a manufacturing method of the semiconductor device of description.
  In this method, the formation of the functional thin film can be realized by low-temperature heat treatment, so that the characteristics of the functional element formed before the functional thin film do not deteriorate.
[0029]
  Claim7The invention described in the above is characterized in that the crystallization step is performed at a temperature equal to or lower than a predetermined temperature that is set so as not to deteriorate the characteristics of the functional element.6It is a manufacturing method of the semiconductor device of description.
  As a result, the deterioration of the characteristics of the functional element can be surely prevented, so that a semiconductor device with good characteristics is realized.
[0030]
  In addition, as a functional element, transistors, such as a field effect transistor, a capacitor, a resistor, etc. can be illustrated.
  Claim8In the described invention, the crystallization step is performed at a predetermined temperature lower than a temperature at which interdiffusion of materials occurs between the functional thin film and a solid adjacent to the functional thin film. Term6 or 7It is a manufacturing method of the semiconductor device of description.
[0031]
  Thereby, since the mutual diffusion of the material between the functional thin film and the solid (such as another thin film) adjacent to the functional thin film can be surely prevented, a semiconductor device having good characteristics is realized.
  Claim9The semiconductor device according to the invention is characterized in that the semiconductor device is a ferroelectric memory device using a ferroelectric thin film as the functional thin film as a charge retention film.6Or8A method for manufacturing a semiconductor device according to any one of the above.
[0032]
According to the present invention, a ferroelectric thin film that is well crystallized by a heat treatment at a relatively low temperature can be used as a charge retention film, so that a good ferroelectric memory device can be realized. In particular, when a writable nonvolatile memory device is realized by utilizing the polarization holding characteristics of the ferroelectric material, significant improvements are realized in terms of inversion polarization characteristics, the number of writable times, low voltage driving, and the like.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a flowchart showing a manufacturing process for manufacturing a ferroelectric memory having the cell structure shown in FIG. An embodiment of the present invention will be described with reference to FIG. 1 and FIG. 13 described above.
[0034]
First, a field oxide film 2 is formed on a semiconductor substrate 1, and further impurity diffusion layers 3 and 4, a gate insulating film 5 and a gate electrode 6 are formed, thereby forming a transistor TR as a functional element (step S1). ). Subsequently, the first interlayer insulating film 7 is formed to cover the gate electrode 6 (step S2).
Thereafter, in order to form the capacitor structure C, for example IrO₂The lower electrode 11 is formed on the first interlayer insulating film 7 at a position substantially above the transistor TR (step S3). A ferroelectric film 10 is laminated on the first interlayer insulating film 7 (step S4). These are patterned in the same pattern.
[0035]
After the formation of the ferroelectric film 10, the upper electrode 12 is formed on the ferroelectric film 10 and patterned by etching (step S5).
Then, for example, SiH_FourA second interlayer insulating film 8 made of an insulator such as silicon oxide is formed on the entire surface of the substrate by a CVD method using the above as a source gas (step S6). Then, contact holes 14 and 15 are opened in the first and second interlayer insulating films 7 and 8 by etching, so that the upper electrode 12 and the impurity diffusion layer 4 are exposed.
[0036]
Next, for example, aluminum is deposited on the second interlayer insulating film 8 by sputtering, and this is patterned by etching to form the first aluminum wiring 9 (step S7).
Then, for example, SiH_FourA third interlayer insulating film 16 made of an insulator such as silicon oxide is formed on the entire surface of the substrate by a CVD method using the above as a source gas (step S8). A contact hole 18 reaching the first aluminum wiring 9 is opened in the third interlayer insulating film 16 by etching.
[0037]
Subsequently, aluminum is deposited on the third interlayer insulating film 16 by, for example, sputtering, and this is patterned by etching to form an aluminum wiring 17 (step S9).
Next, the protective film 19 is formed on the entire surface of the substrate (step S10). The protective film 19 is made of, for example, silicon oxide, and in this case, SiH_FourIt can be formed by a CVD method using the above as a source gas.
[0038]
FIG. 2 is a flowchart for explaining in detail the process of forming the ferroelectric film 10 (step S4). The ferroelectric film 10 is formed by, for example, a sol-gel method. The sol-gel method is a method in which a liquid (sol) raw material is coated on a substrate and fired by heat treatment to obtain a required film.
In the sol-gel method of PZT, for example, Pb (CH which is an organic compound material containing a metal element is used as a starting material._ThreeCOO)₂・ 3H₂O, Zr (n-OC_FourH₉)_Four, Ti (i-OC_ThreeH₇)_FourA solution using 2-methoxyethanol as a solvent is used. This solution is applied onto the substrate by spin coating (step S41), dried at 150 ° C. to 180 ° C. (step S42), and then 400 ° C. (temperature at which crystallization does not occur) in a dry air atmosphere for 30 minutes. Temporary baking is performed (step S43). After repeating this process until the film thickness reaches a predetermined thickness (step S44), an organic substance removal process for removing organic substances in the film is performed (step S45). Finally, main baking (step S46) is performed to crystallize the entire film.
[0039]
In the organic substance removal process (step S45), for example, heat treatment at about 550 ° C. (temperature at which crystallization of the organic compound material does not occur) is performed by rapid thermal annealing in a reduced pressure atmosphere of about 50 Torr. Is executed. That is, the organic substance in the film is volatilized and removed outside the film by the heat treatment in the reduced pressure atmosphere, thereby achieving the organic substance removing process.
[0040]
The main baking (step S46) of the film from which the organic component that inhibits crystallization is removed (film of the inorganic compound material) (step S46) is achieved by heat treatment at a relatively low temperature. As a result, the ferroelectric film 10 can be obtained. In the heat treatment at a temperature of about 550 ° C., there is no possibility that the element characteristics of the transistor TR are deteriorated, and the ferroelectric film 10 and each film adjacent thereto (the lower electrode 11 and the upper electrode 12) are not affected. There is no interdiffusion of materials between them.
[0041]
FIG. 3 is an illustrative view showing a configuration example of a heat treatment apparatus (RTA: Rapid Thermal Anneal) used in the organic substance removal process (step S45). The heat treatment apparatus includes a wafer holder 32 in the processing chamber 31. The wafer holder 32 has a substantially horizontal wafer holding surface 32a on its upper surface, so that the wafer W constituting the semiconductor substrate 1 (after the steps up to step S44 in FIG. 2) can be held on the wafer holding surface 32a. It has become. The wafer holder 32 is composed of a plate-like body attached to the upper end of the rotary shaft 33 arranged along the vertical direction. The wafer holder 32 is rotated while the wafer W is held by rotating the rotary shaft 33 by the rotary drive mechanism 34. It rotates around the axis of rotation.
[0042]
In the processing chamber 31, a plurality of annular infrared lamps 35, 36, and 37 having different diameters are disposed substantially concentrically at positions facing the wafer holding surface 32 a of the wafer holder 32. These infrared lamps 35, 36, and 37 constitute a heating unit that obtains electric power from the lamp driving source 38 and generates infrared rays toward the wafer W, thereby heating the wafer W.
[0043]
An exhaust port 40 is formed in the processing chamber 31. The exhaust port 40 is connected to a decompression mechanism 42 such as a vacuum pump through a decompression pipe 41.
With such a configuration, in the organic substance removing process, the wafer W is held in the wafer holder 32, and the decompression mechanism 42 is driven in a state where the wafer holder 32 is rotationally driven by the rotational drive mechanism 34. For example, the pressure is reduced to about 50 Torr. Further, power is supplied to the infrared lamps 35, 36, and 37 by the lamp driving source 38, and the wafer W is heated. Thereby, the wafer W is rapidly heated to, for example, about 550 ° C. and held at that temperature for a period of 1 second to several minutes. Thereafter, the power supply from the lamp drive source 38 to the infrared lamps 35, 36, and 37 is stopped, and heating is stopped. By such a heat treatment in a reduced-pressure atmosphere, the organic matter in the organic compound material that constitutes the ferroelectric film is sucked out to be an inorganic compound material film.
[0044]
FIG. 4 is an illustrative view showing a configuration example of a heat treatment apparatus used in the main firing step (step S46). The heat treatment apparatus includes a quartz furnace 50, a heater 51 for heating the inside of the furnace 50, a heater driving unit 52 for supplying power to the heater 51, and a plurality of wafers W in the furnace 50. And a wafer holder 53 to be held. With this configuration, the wafer W after the organic substance removal process is performed is placed in the furnace 50, the heater 51 is energized, and the wafer W is heated. In the heating at this time, the temperature of the wafer W is set to about 550 ° C., and the heating is performed for about 30 minutes.
[0045]
As a result of the organic substance removing process (step S45), the crystallization inhibiting factor has been removed, so that the ferroelectric film can be crystallized by heating in the furnace at a relatively low temperature.
FIG. 5 is a characteristic diagram showing the measurement results of the polarization saturation characteristics of the ferroelectric film 10 when the temperatures during the main firing are 550 ° C., 650 ° C., 675 ° C., and 725 ° C. From this characteristic diagram, it is understood that there is no significant difference in the polarization saturation characteristics of the ferroelectric film 10 at any temperature, and good polarization can be produced by firing at a low temperature (about 550 ° C.).
[0046]
FIG. 6 is a characteristic diagram showing measurement results of polarization saturation characteristics of a ferroelectric film manufactured by a conventional method in which main firing is performed without performing organic substance removal processing. FIG. 6 shows the measurement results in each case where the temperatures during the main firing were 675 ° C., 700 ° C., and 725 ° C. From FIG. 6, it is understood that the polarization characteristics greatly depend on the firing temperature, and the desired polarization characteristics cannot be realized unless heat treatment at 700 ° C. or higher is performed.
[0047]
FIG. 7 shows the polarization saturation characteristics when the organic substance removal treatment is performed at a temperature of about 550 ° C. under a reduced pressure of about 50 Torr, and then the ferroelectric film is crystallized by heating in the furnace at about 550 ° C. In other words, the change in polarization when an inversion electric field of various strengths is applied is shown. The value of the applied voltage corresponding to each curve is also shown.
Further, FIG. 8 shows the same polarization saturation characteristics of a ferroelectric film according to the prior art fabricated by performing main firing at about 760 Torr (normal pressure) and about 650 ° C. without performing the organic substance removal treatment. Yes. The value of the applied voltage corresponding to each curve is also shown.
[0048]
From the comparison between FIG. 7 and FIG. 8, it is understood that the ferroelectric film produced by the method of the present embodiment exhibits good polarization characteristics even though the main firing temperature is relatively low. It is understood that the ferroelectric film produced by the method of this embodiment can cause a large polarization by applying a weak electric field. Therefore, in a ferroelectric memory using this ferroelectric film, good writing / erasing can be performed by low voltage driving.
[0049]
FIG. 9 is a diagram showing the film fatigue characteristics of the ferroelectric film. The same polarization saturation characteristics of the ferroelectric film according to the prior art produced by performing the main baking at about 760 Torr (normal pressure) and about 650 ° C. without performing this organic substance removal treatment are shown. The same polarization saturation characteristic of a ferroelectric film according to the prior art produced by performing main baking at about 760 Torr (normal pressure) and about 650 ° C. without performing organic substance removal processing is shown. FIG. 9 shows the change of the switching charge amount with respect to the number of polarization inversion cycles when the polarization inversion voltage is repeatedly applied. The film fatigue characteristics of the ferroelectric film corresponding to the above-described embodiment are represented by the symbol “◯”, and strong by the conventional technique which is fired at about 650 ° C. and about 760 Torr (normal pressure) without performing the organic substance removal treatment. The film fatigue characteristics of the dielectric film are represented by the symbol “♦”.
[0050]
From FIG. 9, it is understood that the ferroelectric film manufactured according to this embodiment is far superior to the ferroelectric film manufactured by the conventional method in film fatigue characteristics. Thereby, it is possible to realize a ferroelectric memory in which the number of rewritable times is significantly improved as compared with the conventional case.
FIG. 10 shows the data retention characteristics of the ferroelectric film,10 ⁸ TimesWhen a reversal electric field is applied to the ferroelectric film in a state after passing through the polarization reversal cycle, a measured value of the amount of charge appearing in the ferroelectric film, and then about 150 in a state where the electric field is applied in one direction. The measured value is shown when an accelerated test is performed at a temperature of 0 ° C. and the same measurement is performed after 10 hours. Similarly to the case of FIG. 9, the measurement result for the ferroelectric film manufactured by the above embodiment is represented by the symbol “◯”, and the measurement result for the ferroelectric film manufactured by the conventional method is , Symbol “◆”.
[0051]
From FIG. 10, the ferroelectric film manufactured according to the above embodiment can maintain the polarization state for a much longer time than the ferroelectric film manufactured by the conventional method, and therefore data retention It will be understood that a ferroelectric memory with good characteristics can be realized.
As described above, according to this embodiment, the organic matter in the organic compound material can be sufficiently removed by the heat treatment under reduced pressure. In addition, since the ferroelectric film 10 is crystallized by performing the main baking process, the ferroelectric film 10 that is crystallized well even if the temperature in the main baking process is relatively low. Obtainable. Therefore, the characteristic degradation of the transistor TR and the characteristic degradation due to the interdiffusion of the material between the ferroelectric film 10 and another film in contact therewith do not occur, thereby improving various characteristics. Can do. As a result, it is possible to realize a ferroelectric memory having characteristics that are remarkably superior to those of the prior art.
[0052]
  Next, referring again to FIG.According to one reference exampleA method will be described.
  thisReference exampleThen, the organic matter removing step and the main baking step are performed simultaneously. That is, the wafer W is held on the wafer holder 32 by the heat treatment apparatus shown in FIG. 3, and the wafer holder 32 is rotated by the rotation drive mechanism 34. At the same time, power is supplied from the lamp driving source 38 to the infrared lamps 35, 36, and 37 to heat the wafer W. Then, the decompression mechanism 42 is operated to decompress the inside of the processing chamber 31 to about 50 Torr, for example.
[0053]
The heating by the infrared lamps 35, 36, and 37 is performed at a temperature (for example, about 550 ° C.) and a time (for example, about 30 minutes) sufficient to crystallize the ferroelectric film 10 on the wafer W.
In the initial period of heating, since organic substances remain in the material of the ferroelectric film 10, crystallization of the film is hindered. When this organic substance is volatilized and removed in the decompressed processing chamber 31, crystallization of the film starts, and heating is continued for a necessary time, whereby the ferroelectric film 10 that is crystallized as a whole is obtained. can get.
[0054]
  Like thisReference exampleIs characterized in that the organic substance removal process and the main baking process are performed simultaneously (or continuously) by one processing device, which can reduce the number of processes and the production cost. it can.
  FIG. 11 shows the first of the present invention.2It is an illustration figure which shows the structural example of the processing apparatus used for the organic substance removal process in this embodiment. This processing apparatus includes a wafer holder 62 in the processing chamber 61. The wafer holder 62 has a substantially horizontal wafer holding surface 62a on its upper surface, so that the wafer W constituting the semiconductor substrate 1 (after the steps up to step S44 in FIG. 2) can be held on the wafer holding surface 62a. It has become. The wafer holder 62 is composed of a plate-like body attached to the upper end of the rotary shaft 63 arranged along the vertical direction. The wafer holder 62 is vertical in a state where the wafer W is held by rotating the rotary shaft 63 by the rotary drive mechanism 64. It rotates around the axis of rotation.
[0055]
The wafer holder 62 incorporates a heater 75. The heater 75 generates heat by obtaining electric power from the heater drive source 76 and constitutes a heat treatment means for heating the wafer W held on the wafer holding surface 62a.
In the processing chamber 61, a plurality of annular ultraviolet lamps 65, 66, 67 having different diameters are arranged substantially concentrically at a position facing the wafer holding surface 62 a of the wafer holder 62. These ultraviolet lamps 65, 66, and 67 constitute an ultraviolet processing unit that obtains electric power from the lamp driving source 68 and generates ultraviolet rays toward the wafer W.
[0056]
FIG. 12 is a bottom view of the ultraviolet lamps 65, 66 and 67. A plurality of ozone discharge ports 69 are arranged at positions avoiding the arrangement positions of the ultraviolet lamps 65, 66, and 67 so as to face the wafer W held on the wafer holding surface 62a. Ozone generated by the ozonizer 70 (see FIG. 11) is supplied to the ozone discharge port 69 via an ozone supply pipe 71. That is, the ozone discharge port 69, the ozonizer 70, and the ozone supply pipe 71 constitute an ozone treatment means as a kind of active oxygen particle treatment means.
[0057]
With the above configuration, in the organic substance removing step (step S45 in FIG. 2), the wafer W is held on the wafer holding surface 62a of the wafer holder 62, and in this state, the heater 75 is energized (heat treatment step). ) And the ultraviolet lamps 65, 66, and 67 are energized by the lamp driving source 68 (an electromagnetic wave supplying step, a step of applying energy other than heat). As a result, heat energy is supplied to the wafer W to perform heat treatment, and ultraviolet energy is supplied to perform non-thermal energy processing at the same time. Thereby, the organic substance in the organic compound material is removed.
[0058]
In the organic substance removing step (step S45), ozone is further supplied from the ozonizer 70 through the ozone supply pipe 71 to the surface of the wafer W from the ozone discharge port 69 (active oxygen particle processing step). Thereby, the wafer W is also subjected to non-thermal energy processing by energy supply from ozone. Thereby, the organic substance in the organic compound material can be more effectively removed.
[0059]
During the processing of the wafer W, the rotation drive mechanism 64 is energized from time to time, and the wafer holder 62 holding the wafer W is rotated. As a result, each part of the wafer W can be uniformly irradiated with ultraviolet rays from the ultraviolet lamps 65, 66, and 67, and ozone and oxygen gas can be supplied uniformly.
When the heater 75 is energized from the heater drive source 76, the temperature of the wafer W causes deterioration of the element characteristics of the transistor TR, and mutual diffusion of the material between the ferroelectric film 10 and each film adjacent thereto. It is set to a temperature that never happens.
[0060]
In this embodiment, if the inside of the processing chamber 61 is depressurized by the depressurization mechanism, the organic substances can be removed more effectively.
After the organic substance removing step, the main baking step (step S46 in FIG. 2) is performed by in-furnace heating by the heat treatment apparatus having the configuration shown in FIG.)Is done.
As described above, according to this embodiment, the organic substance removal treatment is achieved by applying ultraviolet energy and ozone as active oxygen particles to the organic compound material. As a result, thermal stress on the transistor TR and the like can be reduced, which can contribute to improving the characteristics of the ferroelectric memory.
[0061]
  As described above, the present invention2Although one embodiment has been described, the present invention can be implemented in other forms. For example, the above2In the embodiment, in the organic substance removing step, both the irradiation of ultraviolet rays and the supply of ozone are performed together with the heating of the wafer W.,purpleExternal radiationIs omittedMay be.
[0062]
Furthermore, in the above-described embodiment, the case where a ferroelectric memory is manufactured has been described. However, the present invention is not limited to a device using a characteristic of a ferroelectric capacitor, a high dielectric constant material (for example, BST ((BaSr) TiO_Three) Etc.) and other types of semiconductor devices such as various sensors using piezoelectric bodies (such as ZrO) and pyroelectric bodies.
[0063]
In addition, modifications as described in the section of “Means for Solving the Problems and Effects of the Invention” are possible, and besides these, various modifications can be made within the scope of the technical matters described in the claims. Changes can be made.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a manufacturing process for manufacturing a ferroelectric memory.
FIG. 2 is a flowchart illustrating in detail a process of forming a ferroelectric film.
[Figure 3]1'sIt is an illustration figure which shows the structural example of the heat processing apparatus used in embodiment.
FIG. 4 is an illustrative view showing a configuration example of a heat treatment apparatus used in a main firing step in the first embodiment.
FIG. 5 is a characteristic diagram showing measurement results of polarization saturation characteristics of a ferroelectric film when the temperature during main firing is variously changed.
FIG. 6 is a characteristic diagram showing measurement results of polarization saturation characteristics of a ferroelectric film manufactured by a conventional method in which main firing is performed without performing organic substance removal treatment.
FIG. 7 is a characteristic diagram showing a change in polarization when an inversion electric field of various strengths is applied.
FIG. 8 is a characteristic diagram showing a change in polarization with respect to an applied electric field of various strengths in a ferroelectric film manufactured by a conventional method without performing organic substance removal treatment.
FIG. 9 is a diagram showing film fatigue characteristics of a ferroelectric film.
FIG. 10 is a diagram showing data retention characteristics of a ferroelectric film.
FIG. 11 shows the first of the present invention.2It is an illustration figure which shows the structural example of the processing apparatus used for the organic substance removal process in this embodiment.
12 is a bottom view of the ultraviolet lamp and the like of the apparatus of FIG.
FIG. 13 is a cross-sectional view showing a cell structure of a ferroelectric memory.
[Explanation of symbols]
1 Semiconductor substrate
3 Impurity diffusion layer
4 Impurity diffusion layer
6 Gate electrode
10 Ferroelectric film
11 Lower electrode
12 Upper electrode
31 treatment room
32 Wafer holder
33 Rotating shaft
34 Rotation drive mechanism
35, 36, 37 Infrared lamp
38 Lamp drive source
42 Pressure reducing mechanism
50 furnaces
51 Heater
52 Heater drive source
53 Wafer holder
61 treatment room
62 Wafer holder
63 Rotating shaft
64 Rotation drive mechanism
65, 66, 67 UV lamp
68 Lamp drive source
69 Ozone outlet
70 Ozonizer

Claims (9)

A method of firing an organic compound containing a metal element to form a solid of a ferroelectric or high dielectric constant material,
Applying a solution of an organic compound material containing a metal element on a substrate to form a film;
Thereafter, an organic substance removing process is performed on the organic compound material containing the metal element to remove the organic substance in the film by removing the organic substance in the film.
A main calcination of the inorganic compound material obtained by this organic substance removal step and crystallization to obtain a solid of a ferroelectric or high dielectric constant material,
In the organic matter removing step, the organic compound material is heated to a temperature at which crystallization does not occur while the organic matter remains by rapid thermal annealing together with a decompression step in which the organic compound material is placed in a reduced pressure atmosphere. And heat treatment to keep at that temperature is performed in parallel ,
A method for forming a solid of a ferroelectric or high dielectric constant material, wherein the crystallization step is performed after the decompression step . A method of firing an organic compound containing a metal element to form a solid of a ferroelectric or high dielectric constant material,
Applying a solution of an organic compound material containing a metal element on a substrate to form a film;
Thereafter, an organic substance removing process is performed on the organic compound material containing the metal element to remove the organic substance in the film by removing the organic substance in the film.
A main calcination of the inorganic compound material obtained by this organic substance removal step and crystallization to obtain a solid of a ferroelectric or high dielectric constant material,
In the organic substance removing step, the organic compound material is treated with activated oxygen particles, and a heat treatment at a temperature at which crystallization of the organic compound material does not occur is performed in parallel. Alternatively, a method for forming a solid of a high dielectric constant material. 3. The method for forming a solid of a ferroelectric or high dielectric constant material according to claim 2 , wherein the activated oxygen particles are oxygen radicals. The ferroelectric or high dielectric constant material solid according to any one of claims 1 to 3 , wherein the step of forming the film includes a step of pre-firing after drying the solution applied to the substrate. Forming method. On a semiconductor substrate, a method of manufacturing a semiconductor device characterized by comprising the step of forming a functional thin film made of a ferroelectric or high-dielectric constant material of the solid by the method according to any one of claims 1 to 4 . 6. The method of manufacturing a semiconductor device according to claim 5 , further comprising an element forming step for forming a functional element on the semiconductor substrate before the step of forming the functional thin film. The method of manufacturing a semiconductor device according to claim 6 , wherein the crystallization step is performed at a temperature equal to or lower than a predetermined temperature that is set so as not to deteriorate the characteristics of the functional element. The crystallization process, according to claim 6 or 7, characterized in that takes place in a lower predetermined temperature than the temperature at which interdiffusion of the material occurs between the solid adjacent to the functional thin film with the functional thin film Semiconductor device manufacturing method. The semiconductor device manufacturing method of a semiconductor device according to any one of claims 6 to 8 characterized in that it is a ferroelectric memory device using a ferroelectric thin film as the functional thin film as a charge holding film .

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