JP2006303544A - Semiconductor memory device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the lowering of hydrogen barrier property of a film formed on a recess, even when a recess is created on a contact plug. <P>SOLUTION: The method of manufacturing the semiconductor memory device includes:a process to form an interlayer insulating film 106 on a semiconductor substrate 101, a process to form an insulating hydrogen barrier film 107 on the interlayer insulating film 106, the third process to form a contact hole 108, a process to form a plugged film 109 on the insulating hydrogen barrier film 107, so that the inside of the contact hole 108 be embedded, a process to embed a plug 110 into the contact hole 108 by removing the plugged film 109 to become a state, in which a recess 111 is formed, a process to remove the insulating hydrogen barrier film 107 by the depth of the recess 111 to arrange upper surfaces of the plug 110 and the insulating hydrogen barrier film 107 to be flush, and a process to form conductive hydrogen barrier films 112 on the upper surfaces of the plug 110 and insulating hydrogen barrier film 107. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor memory device such as a DRAM or an FeRAM, and more particularly to a stacked capacitor using a ferroelectric or high dielectric film, a semiconductor memory device mounted with the stacked capacitor, and a manufacturing method thereof.

  In the state-of-the-art DRAM, as the cell area is reduced, the manufacturing process becomes complicated and difficult only by the correspondence with the conventional three-dimensional capacitor structure using the silicon oxynitride film. As a result, sufficient capacitor capacity can be obtained. Is becoming impossible.

Therefore, it has become necessary to change the dielectric used for the capacitor to one having a high dielectric constant. Examples of such a material having a high dielectric constant include high dielectric materials such as (Ba, Sr) TiO ₃ and Ta ₂ O ₅ and ferroelectric materials such as oxide ceramics such as PZT, SBT, and BLT. Further, in order to use these dielectric films, as an electrode material to be a base layer for crystal growth of them, metals such as Pt, Pd, Rh, Ni, W, Pt, Pd, Rh, Ni , W, or a metal laminated film such as Ru / RuO ₂ , Ir / IrO ₂ must be used.

  In addition, there is a problem that high dielectric materials and ferroelectric materials are easily reduced by a reducing atmosphere.

  On the other hand, the embedded DRAM and the embedded FeRAM require a hydrogen sinter in order to maintain compatibility with the transistor. Furthermore, there is a step of forming a passivation film on the metal wiring in order to protect the semiconductor device from an external harmful environment such as moisture or dust during the manufacturing process of the memory device. The passivation film is deposited in a hydrogen atmosphere. Also, in the wiring process, many processes are performed in a hydrogen atmosphere.

  These hydrogen gases deteriorate the properties of the memory cell capacitor. That is, hydrogen gas and ions reach the capacitor and react with oxygen atoms forming a dielectric, thereby degrading the characteristics of the capacitor.

  Therefore, in a semiconductor memory device having a stacked capacitor, the capacitor must be surrounded by a film through which hydrogen does not pass (hereinafter referred to as a hydrogen barrier film) to prevent hydrogen from reaching the dielectric. Therefore, it is necessary to surround the capacitor with an insulating hydrogen barrier film and to provide a conductive hydrogen barrier film between the lower electrode and the plug film in order to prevent hydrogen intrusion from the lower electrode (for example, Patent Documents). 1).

  FIG. 6 is a cross-sectional view showing a configuration of a semiconductor memory device having a capacitor having a stack structure using a conventional dielectric film. The insulating hydrogen barrier film is omitted here because it is formed by various methods so as to surround the capacitor.

  In this figure, 601 is a semiconductor substrate, 602 is an STI isolation region, 603 is an impurity region, 604 is a diffusion layer, 604 is a gate oxide film, 606 is a gate electrode, 607 is an interlayer insulating film, 608 is a contact hole, and 609 is a contact hole. Plug burying hole 608, 610 is a conductive hydrogen barrier film, 611 is a lower electrode of a stacked capacitor, 612 is a spacer film of a silicon oxide film, 613 is a ferroelectric film or a high dielectric film, 614 is a stacked capacitor An upper electrode 615 is a capacitor interlayer insulating film.

  In the conventional semiconductor memory device described above, the plug 609 forms a plug film on the contact hole 608 formed in the interlayer insulating film 607 and the upper surface of the interlayer insulating film 607, and the plug film on the upper surface of the interlayer insulating film 607. Is removed by CMP or etchback.

  Next, a contact plug forming process will be described. First, as shown in FIG. 7A, an STI isolation region 702, a transistor impurity region 703, a gate oxide film 704, and a gate electrode 705 are formed on the surface of a semiconductor substrate 701, and an interlayer insulating film 706 is formed thereon.

  Next, as shown in FIG. 7B, the interlayer insulating film 706 is masked to form a contact hole pattern, and this layer is etched by, for example, reactive ion etching (RIE), so that the upper surface of the insulating layer is formed. Then, a contact hole 707 is formed in the wafer to make electrical contact with the specific active region 703.

  Next, as shown in FIG. 7C, a plug film 708 is formed in the contact plug and on the interlayer insulating film by a CVD method, a sputtering method, or a plating method.

Next, as shown in FIG. 7D, the plug film 708 on the interlayer insulating film 706 is removed by the CMP method or the etch back method, and the plug film 709 is left in the contact plug. At this time, at the time of removal by etch back, over-etching is applied, and a recess 710 as shown in FIG. 7D is formed on the plug. At the time of removal by CMP, a certain amount of tungsten film is removed from the contact due to the chemical action of the slurry and the compression action of the polishing pad, resulting in a concave shape 710 as shown in FIG.
JP-A-10-189602

  As described above, in the conventional method for forming a contact plug, a recess is formed on the plug. In the semiconductor memory device, when a hydrogen barrier film is formed on the recess, the conductive hydrogen barrier film 610 is formed in a recess shape as shown in FIG.

  In this portion, there is a problem that the crystallinity of the hydrogen barrier film is unevenly formed by local steps from the recess to a certain film thickness, and the hydrogen barrier property is lowered.

  Therefore, an object of the present invention is made in view of such a problem, and even if a recess is formed on a contact plug made of tungsten or other conductive material, the hydrogen barrier property of a film formed thereon is improved. It is an object of the present invention to provide a semiconductor memory device and a method for manufacturing the same that are not reduced.

  In order to solve the above problems, a semiconductor memory device according to claim 1 of the present invention is a semiconductor memory device having a transistor formed on a semiconductor substrate and a capacitor connected to the transistor, the semiconductor memory device having the transistor on the semiconductor substrate. Impurities of the transistor penetrate through the interlayer insulating film formed to cover the transistor, the insulating hydrogen barrier film formed on the interlayer insulating film, the interlayer insulating film and the insulating hydrogen barrier film A contact hole formed to reach the surface of the diffusion layer, a plug formed in the contact hole, the plug aligned on the same plane, and the upper surface of the insulating hydrogen barrier film, And a conductive hydrogen barrier film formed to be a lower layer.

  3. The semiconductor memory device according to claim 2, wherein the semiconductor memory device includes a transistor formed on a semiconductor substrate and a capacitor that is electrically connected to the transistor, and is an interlayer formed on the semiconductor substrate so as to cover the transistor. An insulating film, an insulating hydrogen barrier film formed on the interlayer insulating film, and formed to penetrate the interlayer insulating film and the insulating hydrogen barrier film to reach the surface of the impurity diffusion layer of the transistor In a recess formed by a contact hole, a plug formed in the contact hole so that the upper surface is positioned lower than the upper surface of the insulating hydrogen barrier film, and the upper surface of the insulating hydrogen barrier film and the upper surface of the plug And a conductive hydrogen barrier film formed by flattening the upper surface so as to be the lowermost layer of the lower electrode of the capacitor.

  4. The semiconductor memory device according to claim 3, wherein the semiconductor memory device includes a transistor formed on a semiconductor substrate and a capacitor connected to the transistor, and is an interlayer formed on the semiconductor substrate so as to cover the transistor. An insulating film, an insulating hydrogen barrier film formed on the interlayer insulating film, and formed to penetrate the interlayer insulating film and the insulating hydrogen barrier film to reach the surface of the impurity diffusion layer of the transistor A contact hole and a conductive hydrogen barrier film formed by filling the inside of the contact hole and flattening the upper surface so as to be the lowermost layer of the lower electrode of the capacitor are provided.

  According to a fourth aspect of the present invention, in the semiconductor memory device according to the first, second, or third aspect, the upper surface of the insulating hydrogen barrier film and the lower surface of the conductive hydrogen barrier film are in direct contact with each other.

  6. The method of manufacturing a semiconductor memory device according to claim 5, wherein the transistor formed on the semiconductor substrate is electrically connected to the capacitor and a hydrogen barrier film for preventing hydrogen from entering the capacitor is provided. A first step of forming an interlayer insulating film on the semiconductor substrate so as to cover the transistor; a second step of forming an insulating hydrogen barrier film on the interlayer insulating film; the interlayer insulating film; A third step of forming a contact hole penetrating the insulating hydrogen barrier film and reaching the surface of the impurity diffusion layer of the transistor; and forming a plug film on the insulating hydrogen barrier film so as to fill the contact hole In a fourth step, the upper surface of the insulating hydrogen barrier film is exposed, and the upper surface of the plug film in the contact hole is exposed to the insulating hydrogen barrier film. A fifth step of burying and forming a plug in the contact hole by removing the plug film so that a recess lower than the upper surface of the film is formed; and the insulating hydrogen by the depth of the recess Removing the barrier film, and forming a conductive hydrogen barrier film on the upper surface of the plug and the upper surface of the insulating hydrogen barrier film, a sixth step of aligning the upper surface of the plug and the insulating hydrogen barrier film on the same plane; A seventh step.

  A method of manufacturing a semiconductor memory device according to claim 6 is a method of manufacturing a semiconductor memory device in which a transistor formed on a semiconductor substrate and a capacitor are electrically connected and a hydrogen barrier film is provided to prevent hydrogen from entering the capacitor. A first step of forming an interlayer insulating film on the semiconductor substrate so as to cover the transistor; a second step of forming an insulating hydrogen barrier film on the interlayer insulating film; the interlayer insulating film; A third step of forming a contact hole penetrating the insulating hydrogen barrier film and reaching the surface of the impurity diffusion layer of the transistor; and forming a plug film on the insulating hydrogen barrier film so as to fill the contact hole In a fourth step, the upper surface of the insulating hydrogen barrier film is exposed, and the upper surface of the plug film in the contact hole is exposed to the insulating hydrogen barrier film. Removing the plug film so that a recess lower than the upper surface of the film is formed, thereby embedding and forming a plug in the contact hole; and on the insulating hydrogen barrier film including the recess A sixth step of forming a conductive hydrogen barrier film, and a seventh step of planarizing the conductive hydrogen barrier film so that the insulating hydrogen barrier film is not exposed.

  The method for manufacturing a semiconductor memory device according to claim 7 is a method for manufacturing a semiconductor memory device in which a transistor formed on a semiconductor substrate and a capacitor are electrically connected and a hydrogen barrier film is provided to prevent hydrogen from entering the capacitor. A first step of forming an interlayer insulating film on the semiconductor substrate so as to cover the transistor; a second step of forming an insulating hydrogen barrier film on the interlayer insulating film; the interlayer insulating film; A third step of forming a contact hole penetrating the insulating hydrogen barrier film and reaching the surface of the impurity diffusion layer of the transistor; and a conductive hydrogen barrier film on the insulating hydrogen barrier film so as to fill the contact hole And a fifth step of planarizing the conductive hydrogen barrier film so that the insulating hydrogen barrier film is not exposed.

  The method of manufacturing a semiconductor memory device according to claim 8 is a method of manufacturing a semiconductor memory device in which a transistor formed on a semiconductor substrate and a capacitor are electrically connected and a hydrogen barrier film is provided to prevent hydrogen from entering the capacitor. A first step of forming a first interlayer insulating film on the semiconductor substrate so as to cover the transistor, a second step of forming an insulating hydrogen barrier film on the first interlayer insulating film, and the insulation A third step of forming a second interlayer insulating film having a thickness corresponding to the depth of the recess generated when the plug is formed on the insulating hydrogen barrier film; the first interlayer insulating film; the insulating hydrogen barrier film; A fourth step of forming a contact hole penetrating through the second interlayer insulating film and reaching the surface of the impurity diffusion layer of the transistor; and the second step so as to fill the contact hole. A fifth step of forming a plug film on the inter-layer insulating film; and an upper surface of the second interlayer insulating film is exposed, and a recess in which the upper surface of the plug film in the contact hole is lower than the upper surface of the second interlayer insulating film is formed. The plug film is removed so as to be formed, so that a plug is embedded in the contact hole, and the second interlayer insulating film is removed until the insulating hydrogen barrier film is exposed. A seventh step of aligning the upper surfaces of the plug and the insulating hydrogen barrier film on the same plane; and an eighth step of forming a conductive hydrogen barrier film on the upper surface of the plug and the upper surface of the insulating hydrogen barrier film. including.

  A method for manufacturing a semiconductor memory device according to claim 9 is the method for manufacturing a semiconductor memory device according to claim 8, wherein the second interlayer insulating film is removed under a condition that the selection ratio to the insulating hydrogen barrier film is 2 or more. .

  A method of manufacturing a semiconductor memory device according to a tenth aspect is the method of manufacturing a semiconductor memory device according to the fifth, sixth, or eighth aspect, wherein the plug film material contains W, and a CMP method is used to remove the plug film.

  The method for manufacturing a semiconductor memory device according to claim 11 is the method for manufacturing a semiconductor memory device according to claim 5, 6 or 7, wherein the insulating hydrogen barrier film is a SiN film.

  A method of manufacturing a semiconductor memory device according to a twelfth aspect is the method of manufacturing a semiconductor memory device according to the sixth aspect, wherein the conductive hydrogen barrier film is formed by a CVD method.

  A method of manufacturing a semiconductor memory device according to claim 13 is the method of manufacturing a semiconductor memory device according to claim 5, 6, 7 or 8, wherein an upper surface of the insulating hydrogen barrier film and a lower surface of the conductive hydrogen barrier film are formed. Are in direct contact.

  According to the semiconductor memory device of the first aspect of the present invention, the plug formed in the contact hole, the plug aligned in the same plane, and the upper surface of the insulating hydrogen barrier film become the lowermost layer of the lower electrode of the capacitor. Since the conductive hydrogen barrier film formed in this way is provided, no concave portion is formed on the plug, and a decrease in the hydrogen barrier property of the conductive hydrogen barrier film can be prevented. For this reason, the electrical characteristics of the capacitor are not deteriorated by the wiring process, hydrogen sintering, or hydrogen during passivation film formation, and a highly reliable capacitor can be realized.

  According to the semiconductor memory device of the second aspect of the present invention, the plug formed in the contact hole so that the upper surface is positioned lower than the upper surface of the insulating hydrogen barrier film, the upper surface of the insulating hydrogen barrier film, and the upper surface of the plug And a conductive hydrogen barrier film formed by flattening the upper surface so as to be the lowermost layer of the lower electrode of the capacitor. The film thickness of the crystalline hydrogen barrier film can be ensured, and the deterioration of the hydrogen barrier property can be prevented. For this reason, the electrical characteristics of the capacitor are not deteriorated by the wiring process, hydrogen sintering, or hydrogen during passivation film formation, and a highly reliable capacitor can be realized.

  According to the semiconductor memory device of the third aspect of the present invention, the conductive memory device is provided with the conductive hydrogen barrier film formed by filling the contact hole and flattening the upper surface so as to be the lowermost layer of the lower electrode of the capacitor. Over the contact hole, a film thickness with a uniform crystallinity of the conductive hydrogen barrier film can be ensured, and deterioration of the hydrogen barrier property can be prevented. For this reason, the electrical characteristics of the capacitor are not deteriorated by the wiring process, hydrogen sintering, or hydrogen during passivation film formation, and a highly reliable capacitor can be realized.

  According to a fourth aspect of the present invention, in the semiconductor memory device according to the first, second, or third aspect, it is preferable that the upper surface of the insulating hydrogen barrier film and the lower surface of the conductive hydrogen barrier film are in direct contact with each other.

  According to the method of manufacturing a semiconductor memory device of the fifth aspect of the present invention, the fourth step of forming the plug film on the insulating hydrogen barrier film so as to fill the contact hole, and the upper surface of the insulating hydrogen barrier film are The plug film is removed so that the recess is formed in such a manner that the upper surface of the plug film in the contact hole is lower than the upper surface of the insulating hydrogen barrier film, so that the plug is embedded in the contact hole. A step, a sixth step of removing the insulating hydrogen barrier film by the depth of the recess and aligning the upper surfaces of the plug and the insulating hydrogen barrier film on the same plane, and an upper surface of the plug and an upper surface of the insulating hydrogen barrier film. And the seventh step of forming the conductive hydrogen barrier film. By eliminating the recess on the plug, the crystallinity of the conductive hydrogen barrier film on the plug is not disturbed. Or it can be realized a dielectric capacitor characteristics with excellent no reliable hydrogen degradation during the passivation film formation.

  According to the method of manufacturing a semiconductor memory device of the sixth aspect of the present invention, the fourth step of forming the plug film on the insulating hydrogen barrier film so as to fill the contact hole, and the upper surface of the insulating hydrogen barrier film are The plug film is removed so that the recess is formed in such a manner that the upper surface of the plug film in the contact hole is lower than the upper surface of the insulating hydrogen barrier film, so that the plug is embedded in the contact hole. A step, a sixth step of forming a conductive hydrogen barrier film on the insulating hydrogen barrier film including the recess, and a seventh step of planarizing the conductive hydrogen barrier film so that the insulating hydrogen barrier film is not exposed. As a result, a conductive hydrogen barrier film is formed in the recess formed on the plug so that the hydrogen barrier property does not deteriorate, and the recess transferred from the recess on the plug onto the conductive hydrogen barrier film is flattened. Rukoto, the less crystalline the disturbance of conductive hydrogen barrier film, wiring process, excellent dielectric capacitor characteristics not reliable hydrogen degradation during hydrogen annealing or passivation film formation can be realized.

  According to the method of manufacturing a semiconductor memory device of the seventh aspect of the present invention, the fourth step of forming the conductive hydrogen barrier film on the insulating hydrogen barrier film so as to fill the contact hole, and the conductive hydrogen barrier film And the fifth step of planarizing the insulating hydrogen barrier film so that the insulating hydrogen barrier film is not exposed. Therefore, the conductive hydrogen barrier film is formed in the contact hole at a thickness that does not deteriorate the hydrogen barrier property, and the concave shape of the contact hole is By flattening the recesses transferred onto the conductive hydrogen barrier film, the crystallinity of the conductive hydrogen barrier film is not disturbed, and there is no deterioration in hydrogen during the wiring process, hydrogen sintering or passivation film formation, and excellent dielectric reliability. Body capacitor characteristics can be realized.

  According to the method of manufacturing the semiconductor memory device of the eighth aspect of the present invention, the fifth step of forming the plug film on the second interlayer insulating film so as to fill the contact hole, and the upper surface of the second interlayer insulating film are The plug film is removed so that a recess is formed in which the upper surface of the plug film in the contact hole is lower than the upper surface of the second interlayer insulating film, so that the plug is embedded in the contact hole. A seventh step of removing the second interlayer insulating film until the insulating hydrogen barrier film is exposed, and aligning the upper surfaces of the plug and the insulating hydrogen barrier film on the same plane, and an upper surface of the plug and the insulating hydrogen barrier film. And the eighth step of forming the conductive hydrogen barrier film on the upper surface. By eliminating the recess on the plug, the crystallinity of the conductive hydrogen barrier film on the plug is not disturbed. Or it can be realized a dielectric capacitor characteristics with excellent no reliable hydrogen degradation during the passivation film formation.

  According to the ninth aspect of the present invention, since the second interlayer insulating film is removed under the condition that the selection ratio with respect to the insulating hydrogen barrier film is 2 or more, it works on the hydrogen barrier property and suppresses the film thickness variation of the insulating hydrogen barrier film. it can.

According to the tenth aspect of the present invention, since the material of the plug film contains W and the CMP method is used for removing the plug film, if the plug film is W, H ₂ O ₂ Due to the wet etching action of an oxidizing agent such as KNO _3, the recesses formed on the plug become deeper.

  According to the eleventh aspect, since the insulating hydrogen barrier film is a SiN film, a recess on the plug is formed due to a low rate of CMP or etchback or a low wet etch rate of HF contained in the cleaning liquid after CMP. Become deeper.

  According to the twelfth aspect, since the conductive hydrogen barrier film is formed by the CVD method, the disorder of the crystallinity of the hydrogen barrier film formed on the concave portion of the plug is small, and the deterioration of the hydrogen barrier property can be further suppressed.

  According to a thirteenth aspect of the present invention, in the method of manufacturing a semiconductor memory device according to the fifth, sixth, seventh, or eighth aspect, it is preferable that the upper surface of the insulating hydrogen barrier film and the lower surface of the conductive hydrogen barrier film are in direct contact with each other.

  A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a process sectional view showing a method of manufacturing a semiconductor memory device according to the first embodiment of the present invention.

  In FIG. 1, 101 is a semiconductor substrate, 102 is an STI isolation region, 103 is an impurity diffusion layer, 104 is a gate oxide film, 105 is a gate electrode, 106 is an interlayer insulating film, 107 is an insulating hydrogen barrier film, and 108 is a contact hole. 109 are plug films, and 112 is a conductive hydrogen barrier film.

  In this method of manufacturing a semiconductor memory device, a transistor formed on the semiconductor substrate 101 and a capacitor (see FIG. 6) are electrically connected, and a hydrogen barrier film that prevents hydrogen from entering the capacitor is provided. The hydrogen barrier film is an insulating hydrogen barrier film 107 and a conductive hydrogen barrier film 112.

  In this case, as shown in FIG. 1A, an interlayer insulating film 106 is formed on the semiconductor substrate 101 so as to cover the transistor (first step). Further, an insulating hydrogen barrier film 107 such as SiN or TiAlOx is preferably formed on the semiconductor substrate 101 including the STI isolation region 102 and the high-concentration impurity diffusion layer 103 covered with the interlayer insulating film 106, preferably a film having a thickness of 10 to 200 nm. The thickness is formed by sputtering or CVD (second step).

  Next, as shown in FIG. 1B, a contact hole 108 having a part of the upper surface of the diffusion layer 103 as a bottom surface passes through the interlayer insulating film 106 and the insulating hydrogen barrier film 107 by dry etching. Form (third step).

  Next, as shown in FIG. 1C, a conductive film (plug film) 109 such as W or polysilicon is formed on the entire surface of the wafer so as to fill the contact hole 108 by CVD, sputtering, or plating. Form (fourth step).

  Next, as shown in FIG. 1D, the conductive film 109 on the insulating hydrogen barrier film 107 is removed by an etch-back method or a CMP method until the upper surface of the insulating hydrogen barrier film 107 is exposed, and contact is made. The conductive film 109 is left inside the plug, and the plug 110 is embedded and formed (fifth step). At this time, the conductive film 109 in the uppermost layer of the contact plug is also removed together with the etching back and CMP over, and the surface of the conductive film 109 becomes lower than the surface of the insulating hydrogen barrier film 107 to form the recess 111. .

  Next, as shown in FIG. 1E, the insulating hydrogen barrier film 107 is removed by the CMP method, the etch back method, and the wet etching method by the same film thickness as the depth of the recess 111, and the insulating hydrogen barrier film 107 is removed. And the upper surface of the plug 110 are aligned on the same plane (sixth step). At this time, it is desirable to completely align the insulating hydrogen barrier film 107 and the plug 110 on the same plane. However, the plug 110 has a concave shape or a convex shape within a range of 1 / 100th of the plug diameter due to variations or the like. It may be.

  Next, as shown in FIG. 1F, a conductive hydrogen barrier film 112 such as TiN, TiAlN, or TiAlON is formed on the entire surface of the wafer by sputtering or CVD (seventh step). By eliminating the recess on the contact plug, the crystallinity of the hydrogen barrier film 112 on the contact plug is not disturbed, and hydrogen during the wiring process, hydrogen sintering, or passivation film formation reduces the reliability of the ferroelectric. Disappear.

Here, if the plug film 109 is W, the recess 111 formed on the plug 110 due to the wet etching action by an oxidizing agent such as H ₂ O ₂ or KNO ₃ that is generally included in the slurry at the time of CMP of W is more formed. Deepen.

  Here, if the insulating hydrogen barrier film 107 is SiN, the recess on the plug 110 is caused by a low CMP or etch back rate or a low wet etch rate of HF contained in the cleaning liquid after CMP. 111 becomes deeper.

  A reference example of the present invention will be described with reference to FIG. FIG. 2 is a process sectional view showing a method of manufacturing a semiconductor memory device according to a reference example of the present invention.

In FIG. 2, 201 is a semiconductor substrate, 202 is an STI isolation region, 203 is an impurity diffusion layer, 204 is a gate oxide film, 205 is a gate electrode, 206 is an interlayer insulating film, 207 is a contact hole, 208 is a plug film, 209 is A plug 211 is a conductive hydrogen barrier film.
In this method of manufacturing a semiconductor memory device, a transistor formed on the semiconductor substrate 201 and a capacitor (see FIG. 6) are electrically connected, and a hydrogen barrier film that prevents hydrogen from entering the capacitor is provided. The hydrogen barrier film is a conductive hydrogen barrier film 211.

  In this case, as shown in FIG. 2A, an interlayer insulating film 206 is formed smoothly on the semiconductor substrate 201 including the STI isolation region 202 and the high-concentration impurity diffusion layer 203 so as to cover the transistors (first step).

  Next, as shown in FIG. 2B, a contact hole 207 having a part of the upper surface of the diffusion layer 203 as its bottom surface is formed through the interlayer insulating film 206 by dry etching (second step).

  Next, as shown in FIG. 2C, a conductive film (plug film) 208 such as W or polysilicon is formed on the entire surface of the wafer so as to fill the contact hole 207 by CVD, sputtering, or plating. (Third step).

  Next, as shown in FIG. 2D, the conductive film 208 on the interlayer insulating film 206 is removed by the etch back method or the CMP method until the upper surface of the insulating hydrogen barrier film 207 is exposed, and the contact plugs are removed. The conductive film 208 is left inside, and a plug 209 is embedded and formed (fourth step). At this time, the uppermost conductive film 208 of the contact plug is also removed, and the surface of the conductive film 208 becomes lower than the surface of the interlayer insulating film 206, thereby forming a recess 210.

  Next, as shown in FIG. 2E, a conductive hydrogen barrier film 211 such as TiN, TiAlN, or TiAlON is formed in the recess 210 and on the interlayer insulating film 206 (fifth step).

  Next, as shown in FIG. 2F, the conductive hydrogen barrier film 211 is polished to a desired thickness so that the interlayer insulating film 206 is not exposed by CMP (sixth step). The desired film thickness is preferably 50 nm or more in order to completely maintain the hydrogen barrier property. However, in consideration of patterning by contact etching or subsequent dry etching, the hydrogen barrier property must be reduced. The thinner one is preferable. By forming the conductive hydrogen barrier film 211 in the concave portion 210 formed on the plug 209 so as to have a thickness that does not decrease the hydrogen barrier property, it is possible to prevent the hydrogen barrier property from decreasing. Furthermore, the concave portion 210 on the plug 209 is transferred to the conductive hydrogen barrier film 211, and the concave portion is generated on the conductive hydrogen barrier film 211. By flattening by CMP, the shape defect can be eliminated. it can.

Here, if the plug film 208 is W, the recess 210 formed on the plug 209 due to the wet etching action by an oxidizing agent such as H ₂ O ₂ or KNO ₃ that is generally included in the slurry during CMP of W. Become deeper.

  Here, if the conductive hydrogen barrier film 211 is formed by a CVD method with good coverage, the crystallinity of the crystallinity of the hydrogen barrier film formed on the recess of the plug 209 is small, and the hydrogen barrier property is reduced. It can be suppressed more.

  A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a process sectional view showing a method of manufacturing a semiconductor memory device according to the second embodiment of the present invention.

  In FIG. 3, 301 is a semiconductor substrate, 302 is an STI isolation region, 303 is an impurity diffusion layer, 304 is a gate oxide film, 305 is a gate electrode, 306 is an interlayer insulating film, 307 is an insulating hydrogen barrier film, and 308 is a contact hole. , 309 are plug films, 310 is a plug, and 312 is a conductive hydrogen barrier film.

  In this method of manufacturing a semiconductor memory device, a transistor and a capacitor (see FIG. 6) formed on a semiconductor substrate 301 are electrically connected to each other, and a hydrogen barrier film that prevents hydrogen from entering the capacitor is provided. The hydrogen barrier film is an insulating hydrogen barrier film 307 and a conductive hydrogen barrier film 312.

  In this case, as shown in FIG. 3A, an interlayer insulating film 306 is formed on the semiconductor substrate 301 so as to cover the transistor (first step). Further, an insulating hydrogen barrier film 307 such as SiN or TiAlOx is preferably formed to a thickness of 10 to 200 nm on the semiconductor substrate 301 including the STI isolation region 302 covered with the interlayer insulating film 306 and the high concentration impurity diffusion layer 303. Then, a sputtering method or a CVD method is used (second step).

  Next, as shown in FIG. 3B, the contact hole 308 having the bottom surface of a part of the upper surface of the diffusion layer 303 penetrates the interlayer insulating film 306 and the insulating hydrogen barrier film 307 and is dry-etched. (Third step).

  Next, as shown in FIG. 3C, a conductive film (plug film) 309 such as W or polysilicon is formed on the entire surface of the wafer so as to fill the contact hole 308 by CVD, sputtering, or plating. (4th process).

  Next, as shown in FIG. 3D, the conductive film 308 on the insulating hydrogen barrier film 307 is removed by an etch back method or a CMP method until the upper surface of the insulating hydrogen barrier film 307 is exposed, and contact is made. The conductive film 308 is left inside the plug, and the plug 310 is embedded and formed (fifth step). At this time, the uppermost conductive film 308 of the contact plug is also removed together, and the surface of the conductive film 308 becomes lower than the surface of the insulating hydrogen barrier film 307 to form a recess 311.

  Next, as shown in FIG. 3E, a conductive hydrogen barrier film 312 such as TiN, TiALN, or TiAlON is formed in the recess 311 and on the insulating hydrogen barrier film 307 (sixth step).

  Next, as shown in FIG. 3F, the conductive hydrogen barrier film 312 is polished to a desired thickness so that the insulating hydrogen barrier film 307 is not exposed by CMP (seventh step). The desired film thickness is preferably 50 nm or more in order to completely maintain the hydrogen barrier property. However, in consideration of patterning by contact etching or subsequent dry etching, the hydrogen barrier property must be reduced. The thinner one is preferable. By forming the conductive hydrogen barrier film 312 in the recess 311 formed on the plug 310 so as to have a film thickness that does not decrease the hydrogen barrier property, the hydrogen barrier property can be prevented from decreasing. Further, the concave portion 311 on the plug 310 is transferred to the conductive hydrogen barrier film 312 and the concave portion 311 is generated on the conductive hydrogen barrier film 312. By flattening by CMP, the shape defect can be eliminated. it can.

Here, if the plug film 308 is W, there is a recess 311 formed on the plug 310 by a wet etching action by an oxidizing agent such as H ₂ O ₂ or KNO ₃ that is generally included in the slurry during CMP of W. Become deeper.

  Here, if the insulating hydrogen barrier film 307 is SiN, the recess on the plug 310 is caused by a low CMP or etch back rate or a low wet etch rate of HF contained in the cleaning liquid after CMP. 311 becomes deeper.

  Here, if the conductive hydrogen barrier film 312 is formed by a CVD method with good coverage, the crystallinity of the crystallinity of the hydrogen barrier film formed on the depression of the plug 310 is reduced, and the hydrogen barrier property is reduced. It can be suppressed more.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a process sectional view showing a method of manufacturing a semiconductor memory device according to the third embodiment of the present invention.

  In FIG. 4, 401 is a semiconductor substrate, 402 is an STI isolation region, 403 is an impurity diffusion layer, 404 is a gate oxide film, 405 is a gate electrode, 406 is an interlayer insulating film, 407 is an insulating hydrogen barrier film, and 408 is a contact hole. , 409 are conductive hydrogen barrier films.

  In this method for manufacturing a semiconductor memory device, a transistor formed on a semiconductor substrate 401 and a capacitor (see FIG. 6) are electrically connected, and a hydrogen barrier film that prevents hydrogen from entering the capacitor is provided. The hydrogen barrier films are an insulating hydrogen barrier film 407 and a conductive hydrogen barrier film 409.

  In this case, as shown in FIG. 4A, an interlayer insulating film 406 is formed on the semiconductor substrate 401 so as to cover the transistor (first step). Further, an insulating hydrogen barrier film 407 such as SiN or TiAlOx is preferably formed to a thickness of 10 to 200 nm on the semiconductor substrate 401 including the STI isolation region 402 and the high concentration impurity diffusion layer 403 covered with the interlayer insulating film 406. Then, a sputtering method or a CVD method is used (second step).

  Next, as shown in FIG. 4B, the contact hole 408 having the bottom surface of a part of the upper surface of the diffusion layer 403 passes through the interlayer insulating film 406 and the insulating hydrogen barrier film 407 and is dry-etched. (Third step).

  Next, as shown in FIG. 4C, a conductive hydrogen barrier film 409 such as TiN, TiAlN, or TiAlON is formed on the entire surface of the wafer so as to fill the contact holes (fourth step).

  Next, as shown in FIG. 4D, the conductive hydrogen barrier film 409 is polished to a desired film thickness using the CMP method so that the insulating hydrogen barrier film 407 is not exposed (fifth step). The desired film thickness is preferably 50 nm or more in order to completely maintain the hydrogen barrier property. However, in consideration of patterning by contact etching or subsequent dry etching, the hydrogen barrier property must be reduced. The thinner one is preferable. By forming a conductive hydrogen barrier film in the contact hole 408 and on the insulating hydrogen barrier film 407 so as to have a thickness that does not deteriorate the hydrogen barrier property, a decrease in the hydrogen barrier property can be prevented. Further, in the conductive hydrogen barrier film 409, a recess is formed on the conductive hydrogen barrier film 409 on the portion buried in the contact hole 408. Can be eliminated.

  Here, if the conductive hydrogen barrier film 409 is formed by a CVD method with good coverage, the crystallinity of the hydrogen barrier film formed over the contact hole 408 is not disturbed, and the hydrogen barrier property is not lowered.

  A fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a process sectional view showing a method of manufacturing a semiconductor memory device according to the fourth embodiment of the present invention.

  In FIG. 4, 501 is a semiconductor substrate, 502 is an STI isolation region, 503 is an impurity diffusion layer, 504 is a gate oxide film, 504 is a gate electrode, 506 is a first interlayer insulating film, 507 is an insulating hydrogen barrier film, and 508 is The second interlayer insulating film, 509 is a contact hole, 510 is a plug film, 511 is a plug, and 513 is a conductive hydrogen barrier film.

  In this method for manufacturing a semiconductor memory device, a transistor formed on a semiconductor substrate 501 is electrically connected to a capacitor (see FIG. 6), and a hydrogen barrier film that prevents hydrogen from entering the capacitor is provided. The hydrogen barrier film is an insulating hydrogen barrier film 507 and a conductive hydrogen barrier film 513.

  In this case, as shown in FIG. 5A, a first interlayer insulating film 506 is formed on the semiconductor substrate 501 so as to cover the transistor (first step). Further, an insulating hydrogen barrier film 507 such as SiN or TiAlOx is preferably formed to a thickness of 10 to 100 nm on the semiconductor substrate 501 including the STI isolation region 502 covered with the first interlayer insulating film 506 and the high concentration impurity diffusion layer 503. Thickness is formed by sputtering or CVD (second step). Next, the second interlayer insulating film 508 is formed by the same film thickness as the depth of the recess generated when the plug is formed (third process).

  Next, as shown in FIG. 5B, a contact hole 509 having a part of the upper surface of the diffusion layer 503 as its bottom surface is formed into a first interlayer insulating film 506, an insulating hydrogen barrier film 507, and a second interlayer insulating film. The film 508 is penetrated and formed by dry etching (fourth step).

  Next, as shown in FIG. 5C, a conductive film (plug film) 510 such as W or polysilicon is formed on the entire surface of the wafer so as to fill the contact hole 509 by CVD, sputtering, or plating. (5th process).

  Next, as shown in FIG. 5D, the conductive film 510 on the insulating hydrogen barrier film 507 is removed by the etch-back method or the CMP method until the upper surface of the second interlayer insulating film 508 is exposed, and the contact is made. The conductive film 510 is left inside the plug, and the plug 511 is embedded and formed (sixth step). At this time, the uppermost conductive film 510 of the contact plug is also removed together, and the surface of the conductive film 510 becomes lower than the surface of the insulating hydrogen barrier film 507 to form a recess 512.

  Next, as shown in FIG. 5E, the upper surface of the insulating hydrogen barrier film 507 and the plug 511 are flush with each other by removing the second interlayer insulating film 508 by wet etching, CMP, or etch back. (Seventh step). At this time, it is desirable to completely align the insulating hydrogen barrier film 507 and the plug 511 on the same plane, but the plug 511 has a concave shape or a convex shape within a range of 1 / 100th of the plug diameter due to variations or the like. It may be.

  Next, as shown in FIG. 5F, a conductive hydrogen barrier film 513 such as TiN, TiALN, or TiAlON is formed on the plug 511 and the insulating hydrogen barrier film 507 (eighth step). By eliminating the recess on the contact plug, the crystallinity of the conductive hydrogen barrier film 513 thereon is not disturbed, and hydrogen during the wiring process, hydrogen sintering, or passivation film formation reduces the reliability of the ferroelectric. Things will disappear.

  Here, the second interlayer insulating film 508 is removed under the condition that the selection ratio with respect to the insulating hydrogen barrier film 507 is 2 or more, so that the effect on the hydrogen barrier property is suppressed, and the film thickness variation of the insulating hydrogen barrier film 507 is suppressed. be able to.

  INDUSTRIAL APPLICABILITY The semiconductor memory device and the manufacturing method thereof according to the present invention have an effect that a capacitor having excellent reliability can be realized without deterioration of the electrical characteristics of the capacitor due to hydrogen during the wiring process, hydrogen sintering or passivation film formation. It is useful as a semiconductor memory device such as DRAM or FeRAM.

It is process sectional drawing which shows the manufacturing method of the semiconductor memory device of 1st Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the semiconductor memory device of the reference example of this invention. It is process sectional drawing which shows the manufacturing method of the semiconductor memory device of 2nd Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the semiconductor memory device of 3rd Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the semiconductor memory device of 4th Embodiment of this invention. It is sectional drawing which shows the conventional semiconductor memory device. It is process sectional drawing which shows the manufacturing method of the conventional contact plug.

Explanation of symbols

101 Semiconductor substrate 102 STI isolation region 103 Impurity diffusion layer 104 Gate oxide film 105 Gate electrode 106 Interlayer insulating film 107 Insulating hydrogen barrier film 108 Contact hole 109 Plug film 110 Plug 111 Recess 112 on plug 112 Conductive hydrogen barrier film 506 First Interlayer insulating film 508 Second interlayer insulating film 604 Diffusion layer 611 Stacked capacitor lower electrode 612 Spacer film 613 High dielectric or ferroelectric 614 Stacked capacitor upper electrode 615 Capacitor interlayer

Claims (13)

A semiconductor memory device having a transistor formed on a semiconductor substrate and a capacitor conducting to the transistor,
An interlayer insulating film formed on the semiconductor substrate so as to cover the transistor;
An insulating hydrogen barrier film formed on the interlayer insulating film;
A contact hole formed so as to penetrate the interlayer insulating film and the insulating hydrogen barrier film and reach the impurity diffusion layer surface of the transistor; a plug formed in the contact hole;
A semiconductor memory device comprising: the plug arranged on the same plane; and a conductive hydrogen barrier film formed on the upper surface of the insulating hydrogen barrier film so as to be a lowermost layer of the lower electrode of the capacitor. A semiconductor memory device having a transistor formed on a semiconductor substrate and a capacitor conducting to the transistor,
An interlayer insulating film formed on the semiconductor substrate so as to cover the transistor;
An insulating hydrogen barrier film formed on the interlayer insulating film;
A contact hole formed so as to penetrate the interlayer insulating film and the insulating hydrogen barrier film and reach the impurity diffusion layer surface of the transistor;
A plug formed in the contact hole such that the upper surface is positioned lower than the upper surface of the insulating hydrogen barrier film;
A conductive hydrogen barrier film formed by filling the recess formed by the upper surface of the insulating hydrogen barrier film and the upper surface of the plug and planarizing the upper surface so as to be the lowermost layer of the lower electrode of the capacitor; Semiconductor memory device. A semiconductor memory device having a transistor formed on a semiconductor substrate and a capacitor conducting to the transistor,
An interlayer insulating film formed on the semiconductor substrate so as to cover the transistor;
An insulating hydrogen barrier film formed on the interlayer insulating film;
A contact hole formed so as to penetrate the interlayer insulating film and the insulating hydrogen barrier film and reach the impurity diffusion layer surface of the transistor;
A semiconductor memory device comprising: a conductive hydrogen barrier film embedded in the contact hole and formed to be a lowermost layer of the lower electrode of the capacitor.   4. The semiconductor memory device according to claim 1, wherein an upper surface of the insulating hydrogen barrier film and a lower surface of the conductive hydrogen barrier film are in direct contact with each other. A method for manufacturing a semiconductor memory device, wherein a transistor formed on a semiconductor substrate is electrically connected to a capacitor and a hydrogen barrier film for preventing hydrogen from entering the capacitor is provided,
A first step of forming an interlayer insulating film on the semiconductor substrate so as to cover the transistor;
A second step of forming an insulating hydrogen barrier film on the interlayer insulating film;
A third step of forming a contact hole penetrating the interlayer insulating film and the insulating hydrogen barrier film and reaching the impurity diffusion layer surface of the transistor;
A fourth step of forming a plug film on the insulating hydrogen barrier film so as to fill the contact hole;
Removing the plug film so that the upper surface of the insulating hydrogen barrier film is exposed and the upper surface of the plug film in the contact hole is formed with a recess formed lower than the upper surface of the insulating hydrogen barrier film; A fifth step of embedding and forming a plug in the contact hole;
A sixth step of removing the insulating hydrogen barrier film by the depth of the recess, and aligning the upper surface of the plug and the insulating hydrogen barrier film on the same plane;
A method of manufacturing a semiconductor memory device, comprising: a seventh step of forming a conductive hydrogen barrier film on an upper surface of the plug and an upper surface of the insulating hydrogen barrier film. A method for manufacturing a semiconductor memory device, wherein a transistor formed on a semiconductor substrate is electrically connected to a capacitor and a hydrogen barrier film for preventing hydrogen from entering the capacitor is provided,
A first step of forming an interlayer insulating film on the semiconductor substrate so as to cover the transistor;
A second step of forming an insulating hydrogen barrier film on the interlayer insulating film;
A third step of forming a contact hole penetrating the interlayer insulating film and the insulating hydrogen barrier film and reaching the impurity diffusion layer surface of the transistor;
A fourth step of forming a plug film on the insulating hydrogen barrier film so as to fill the contact hole;
Removing the plug film so that the upper surface of the insulating hydrogen barrier film is exposed and the upper surface of the plug film in the contact hole is formed with a recess formed lower than the upper surface of the insulating hydrogen barrier film; A fifth step of embedding and forming a plug in the contact hole;
A sixth step of forming a conductive hydrogen barrier film on the insulating hydrogen barrier film including the recess;
And a seventh step of planarizing the conductive hydrogen barrier film so that the insulating hydrogen barrier film is not exposed. A method for manufacturing a semiconductor memory device, wherein a transistor formed on a semiconductor substrate is electrically connected to a capacitor and a hydrogen barrier film for preventing hydrogen from entering the capacitor is provided,
A first step of forming an interlayer insulating film on the semiconductor substrate so as to cover the transistor;
A second step of forming an insulating hydrogen barrier film on the interlayer insulating film;
A third step of forming a contact hole penetrating the interlayer insulating film and the insulating hydrogen barrier film and reaching the impurity diffusion layer surface of the transistor;
A fourth step of forming a conductive hydrogen barrier film on the insulating hydrogen barrier film so as to fill the contact hole;
And a fifth step of planarizing the conductive hydrogen barrier film so that the insulating hydrogen barrier film is not exposed. A method for manufacturing a semiconductor memory device, wherein a transistor formed on a semiconductor substrate is electrically connected to a capacitor and a hydrogen barrier film for preventing hydrogen from entering the capacitor is provided,
Forming a first interlayer insulating film on the semiconductor substrate so as to cover the transistor;
A second step of forming an insulating hydrogen barrier film on the first interlayer insulating film;
A third step of forming a second interlayer insulating film having a film thickness corresponding to the depth of the recess generated when the plug is formed on the insulating hydrogen barrier film;
A fourth step of forming a contact hole that penetrates the first interlayer insulating film, the insulating hydrogen barrier film, and the second interlayer insulating film and reaches the surface of the impurity diffusion layer of the transistor;
A fifth step of forming a plug film on the second interlayer insulating film so as to fill the contact hole;
Removing the plug film so that the upper surface of the second interlayer insulating film is exposed and the upper surface of the plug film in the contact hole is in a state where a recess is formed lower than the upper surface of the second interlayer insulating film; A sixth step of embedding a plug in the contact hole;
A seventh step of removing the second interlayer insulating film until the insulating hydrogen barrier film is exposed, and aligning the upper surfaces of the plug and the insulating hydrogen barrier film on the same plane;
A method of manufacturing a semiconductor memory device, comprising: an eighth step of forming a conductive hydrogen barrier film on an upper surface of the plug and an upper surface of the insulating hydrogen barrier film.   9. The method of manufacturing a semiconductor memory device according to claim 8, wherein the second interlayer insulating film is removed under a condition that a selection ratio with the insulating hydrogen barrier film is 2 or more.   9. The method of manufacturing a semiconductor memory device according to claim 5, wherein a material of the plug film includes W, and a CMP method is used to remove the plug film.   8. The method of manufacturing a semiconductor memory device according to claim 5, wherein the insulating hydrogen barrier film is a SiN film.   The method of manufacturing a semiconductor memory device according to claim 6, wherein the conductive hydrogen barrier film is formed by a CVD method.   9. The method of manufacturing a semiconductor memory device according to claim 5, wherein an upper surface of the insulating hydrogen barrier film and a lower surface of the conductive hydrogen barrier film are in direct contact with each other.

Images