KR100289975B1 - Method of manufacturing semiconductor device and semiconductor device - Google Patents

Abstract

When fabricating a ferroelectric memory cell having a bit line preformed and upper electrode connection structure, it is possible to prevent deterioration of characteristics of the ferroelectric capacitor and to enable process integration.

When manufacturing the ferroelectric memory cell MC in which one fast transistor Q and one ferroelectric capacitor C are connected in series, the contact plug 15 is embedded in the insulating film 13 on the source region S of the fast transistor, and the contact plug 15 The upper end surface of the ()) and the capacitor upper electrode 19 are connected by the electrode wiring 22.

Description

TECHNICAL MANUFACTURING METHOD AND SEMICONDUCTOR DEVICE OF TECHNICAL DEVICE {METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE AND SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device and a semiconductor device manufactured by the same, and more particularly, to a method of forming a connection wiring structure between transistors and capacitors in a ferroelectric memory cell using a ferroelectric in an insulating film of an information storage capacitor, and a connection wiring structure thereof. For example, it is applied to a ferroelectric memory (FRAM) having an array of ferroelectric memory cells.

In recent years, research into nonvolatile memory cells (ferroelectric memory cells) using ferroelectric thin films having a perovskite structure as inter-electrode insulating films of information storage capacitors has been actively conducted.

The ferroelectric film has the characteristic that the electric polarization once generated when the electric field is applied remains even if the electric field is not applied, and that the direction of the polarization is reversed when a strong electric field is applied to some extent in the opposite direction to the electric field.

Focusing on the polarization characteristic in which the polarization direction of the dielectric is reversed, a technique for realizing a nonvolatile ferroelectric memory cell by using a ferroelectric for an information storage capacitor insulating film of a memory cell has been developed.

This ferroelectric memory cell has a structure in which a DRAM cell capacitor is replaced with a ferroelectric capacitor, and a method (data destruction readout) for extracting charges in the case of polarization inversion or non-inversion from a ferroelectric capacitor through a MOS transistor for a transfer gate. In this case, the stored data stored in the memory cells is not lost even when the operating power is turned off.

By the way, the above-described ferroelectric memory is capable of high speed and low power consumption operation, and is expected to achieve high integration, and therefore, it is necessary to examine a manufacturing process with less memory cell area and less degradation of the ferroelectric.

Conventionally, as a structure of a ferroelectric memory cell, there are (1) a bit line post-forming structure in which ferroelectric capacitors are arranged under a bit line, and (2) a bit line preforming structure in which bit lines are arranged under a ferroelectric capacitor.

When fabricating the ferroelectric memory cell having the bit line post-forming structure, a ferroelectric capacitor is disposed on the upper layer of the fast transistor, the lower electrode and the fast transistor are connected with a polysilicon plug, and then a bit line is formed on the ferroelectric capacitor. do.

When the ferroelectric capacitor is formed, a ferroelectric thin film is formed after forming the lower electrode of the ferroelectric capacitor using Pt (platinum) on a polysilicon plug, but when the ferroelectric thin film is formed to perform crystallization, high temperature Oxygen annealing is required.

Here, when PZT (lead zirconate titanate) is used as the ferroelectric material, deterioration of capacitor characteristics occurs due to the occurrence of defects caused by diffusion of Pb in PZT when oxidation is insufficient. Since sufficient oxidation is performed in order to avoid this, the required oxygen annealing temperature is usually 600 ° C to 700 ° C.

In addition, when using bismuth layer type compounds, such as SBT (strontium bismuth tantalum) as a ferroelectric material, the required oxygen annealing temperature is high temperature of -800 degreeC normally.

However, during the high temperature oxygen annealing as described above, there is a problem that the lower electrode using Pt reacts with the polysilicon plug to be silicided or the polysilicon plug is oxidized.

On the other hand, when manufacturing the ferroelectric memory cell of the bit line preformed structure, the bit line is formed on the upper layer of the fast transistor, and the ferroelectric capacitor is formed on the layer of the bit line.

At this time, when the lower electrode (for example, Pt) and the fast transistor of the ferroelectric capacitor are connected by the polysilicon plug, the same problems as those of the bit line post-forming structure arise.

On the other hand, the upper electrode connection structure which connects the upper electrode of a ferroelectric capacitor and a fast transistor directly with the local electrode wiring which consists of a buried wiring is proposed. This structure is characterized in that the pattern layout of the ferroelectric capacitor has a relatively high degree of freedom, and the fine structure can be realized by arranging the ferroelectric capacitor on both the fast transistor region and the element isolation region.

When the bit line preformation and upper electrode connection structure are realized, the capacitor protective film is deposited after forming the lower electrode (plate electrode) of the ferroelectric capacitor to the upper electrode. Thereafter, in order to form local electrode wiring for directly connecting the upper electrode and the fast transistor, a contact portion with the upper electrode and a contact portion with the active layer of the fast transistor are opened in the capacitor protective film, and the wiring film is deposited and then patterned.

When the bit line pre-formed upper electrode connection structure is realized, as described above, when the lower electrode (for example, Pt) and the fast transistor of the ferroelectric capacitor are connected by a polysilicon plug, the lower electrode is connected to the polysilicon plug. It does not generate | occur | produce a problem that it reacts and silicides, or a polysilicon plug oxidizes.

However, in view of aspect ratio and step coverage accompanying miniaturization, it is difficult to form local electrode wiring for directly connecting the upper electrode and the fast transistor as described above.

In addition, when PZT or BST is used as the ferroelectric material, a reducing atmosphere in various CVD (chemical vapor growth) processes performed when forming electrode wirings after the formation of the ferroelectric thin film becomes a problem, and the ferroelectric material causes characteristic deterioration in accordance with the reduction reaction. There is a problem.

That is, when forming the local electrode wiring for connecting the upper electrode and the fast transistor, the W plug by W (tungsten) film formation in a strong reducing atmosphere (hydrogen-based gas) using the metal CVD apparatus used in DRAM If it is to be buried, it cannot be used because it causes deterioration of characteristics (electrical properties such as residual polarization amount) of the ferroelectric capacitor.

On the other hand, even when forming the aluminum wiring film by using MO (Metal Organic) CVD when forming the local electrode wiring for connecting the upper electrode and the fast transistor, it is not said that there is no reducing atmosphere (source The hydrogen group component, including the material, cannot be completely removed), which also causes deterioration of the characteristics of the ferroelectric capacitor.

In the case where PZT or BST is used as the ferroelectric material, Pt, Ir, Ir oxide, Ru oxide and the like are generally used as the upper electrode of the ferroelectric capacitor. However, it is quite difficult to finely process these materials to submicron level on the order of 0.5 μm by RIE (reactive ion etching), ion milling, ECR, etc., and in particular, Pt is very difficult because of the hard material, which makes it difficult to refine the ferroelectric capacitor. Become. However, when designing a highly integrated ferroelectric memory, miniaturization of the ferroelectric memory cell is inevitable, and miniaturization of the upper electrode of the ferroelectric capacitor is an important problem for miniaturization of the memory cell.

As described above, the conventional ferroelectric memory having the bit line preformed and upper electrode connection structure prevents the deterioration of the characteristics of the ferroelectric capacitor and integrates the process.

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and when manufacturing a ferroelectric memory cell having a bit line preformed and upper electrode connection structure, the semiconductor prevents deterioration of characteristics of the ferroelectric capacitor and enables process integration. It is an object to provide a method for producing a device and a semiconductor device manufactured according to the same.

A semiconductor device manufacturing method of the present invention comprises the steps of forming a MOS transistor having a drain region and a source region composed of an impurity diffusion region in a surface layer portion of a semiconductor substrate, and then forming a first insulating film on the semiconductor substrate. Forming a bit line on the first insulating film having a lower end contacting the one end region of the MOS transistor on the first insulating film, forming a second insulating film on the bit line and on the first insulating film; Selectively opening a contact hole in the second insulating film and the first insulating film, and forming a capacitor contact plug having a lower end contacting the other end region of the MOS transistor; and thereafter, a lower electrode and a ferroelectric material on the semiconductor substrate. Forming a ferroelectric capacitor having an inter-electrode insulating film and an upper electrode using a material; and the ferroelectric capacitor It characterized in that it comprises a step of forming an electrode wiring for connecting between the upper surface of the upper capacitor electrode and the contact plug of the emitter.

In addition, a method of manufacturing a semiconductor device of the present invention includes a plurality of memory cells each having a ferroelectric capacitor for information storage and a MOS transistor for charge transfer using a ferroelectric material as an inter-electrode insulating film, and the memory cells in the same row, respectively. A plurality of word lines commonly connected to the gates of the MOS transistors, a plurality of capacitor plate lines commonly connected to the ferroelectric capacitors of the memory cells in the same row, and common to one side of the MOS transistors of the memory cells in the same column, respectively A method of manufacturing a ferroelectric memory having a plurality of bit lines connected to each other, comprising: two drain channel source regions each constituting a MOS transistor in a direction substantially parallel to a bit line direction at a predetermined position of a surface layer portion of a semiconductor substrate; In a straight shape while sharing the drain region in the center In this case, the step of defining the cell array region by regularly arranging the plurality of drain channel source regions in a checkerboard shape as a whole, and in the plurality of drain channel source regions in the same row of the cell array region, respectively. Forming a plurality of word lines having gate electrode portions stacked on the channel region of each of the MOS transistors through a gate insulating film in a direction substantially parallel to each other, forming a first insulating film on the word lines, and A plurality of bit lines contacting common drain regions in the plurality of drain channel and source regions in the same column of the cell array region are substantially parallel to each other on the first insulating film, and are substantially orthogonal to the plurality of word lines. Forming a second insulating film on the bit line and on the first insulating film; And embedding a capacitor contact plug having a lower end contacting the source region in the drain channel source region in the second insulating film and the first insulating film, and capping on the capacitor contact plug and the second insulating film. Forming a third insulating film, and a plurality of capacitor plate lines serving as lower electrodes shared by ferroelectric capacitors in a plurality of memory cells in the same row on the third insulating film in a direction substantially parallel to the word lines; And forming a plurality of ferroelectric capacitors having the lower electrode, the inter-electrode insulating layer using the ferroelectric material, and the upper electrode corresponding to each unit cell of the cell array region, and protecting the surface of the ferroelectric capacitor. Forming a fourth insulating film, and said ferroelectric capacitor of said fourth insulating film Opening the first contact hole for the electrode wiring connection in a portion corresponding to the upper electrode of the second electrode; and a second for the electrode wiring connection in the portion corresponding to the capacitor contact plug of the fourth insulating film and the third insulating film. A step of opening a contact hole and a step of depositing an electrode wiring material on the fourth insulating film and patterning electrode wiring for connecting between the upper electrode of the ferroelectric capacitor and the upper end surface of the capacitor contact plug for each of the unit cells. Characterized in that.

In addition, a semiconductor device of the present invention includes a MOS transistor having a drain region and a source region formed of an impurity diffusion region formed in a surface layer portion of a semiconductor substrate, a first insulating film formed on the MOS transistor, and a buried formation in the first insulating film. A ferroelectric capacitor having a capacitor contact plug having a lower end contacting one of the drain region and the source region, an upper electrode side of the first insulating film, and an interelectrode insulating film made of a ferroelectric material and an upper electrode; And electrode wiring connecting an upper end of the capacitor contact plug and an upper electrode of the ferroelectric capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing an example of a planar pattern of a part of a cell array in a cell array manufacturing process for a large-capacity ferroelectric memory employing a ferroelectric memory cell according to the first embodiment of the present invention.

FIG. 2 shows a part of the planar pattern in the process according to the process of FIG. 1; FIG.

3 shows a part of the planar pattern in the process according to the process of FIG.

4 is a view showing a part of a cross section in an example of a manufacturing process of the cell shown in FIGS.

FIG. 5 shows a part of a cross section in the process according to the process of FIG. 5; FIG.

6 shows a part of a cross section in a process according to the process of FIG. 5;

7 shows a part of a cross section in a process according to the process of FIG. 6;

8 is a cross-sectional view showing a part of a cross section by extracting a part of the process of FIG.

Fig. 9 is a circuit diagram showing an equivalent circuit of a ferroelectric memory cell of one transistor and one capacitor configuration.

FIG. 10 is a circuit diagram illustrating an equivalent circuit of the array of ferroelectric memory cells of FIG. 9 and a portion of a peripheral circuit thereof. FIG.

FIG. 11 is a diagram showing an applied electric field and a state of electrical polarization of a ferroelectric capacitor in order to explain the principle of a write operation of a two transistor / two capacitor type ferroelectric memory cell using two memory cells of FIG.

FIG. 12 is a diagram showing the applied electric field and the state of electrical polarization of a ferroelectric capacitor in order to explain the principle of the read operation of a two transistor / two capacitor type ferroelectric memory cell using two memory cells of FIG.

FIG. 13 is a waveform diagram showing an example of a voltage waveform applied to the plate line PL during the write operation shown in FIG. 11 and the read operation shown in FIG.

Fig. 14 is a diagram showing the overall system configuration of the RFID system.

15 shows a detailed internal circuit of the transponder.

<Explanation of symbols for main parts of drawing>

1: semiconductor substrate

2: Separation oxide film between devices

3: gate oxide film

4: P-doped polysilicon

5: WSi

6, 7: insulating film for gate electrode protection

9, 10: insulating film

11: barrier metal film

13: insulating film for planarization

14: barrier metal film

15: Capacitor contact plug

16: insulating film for cap

17: lower electrode

18: ferroelectric thin film

19: upper electrode

16a, 19a: opening for electrode wiring connection

20a: insulating film for filling the upper electrode

20: insulating film for capacitor protection

21: barrier metal film

22: electrode wiring

23: passivation film

SDG: active area

D: impurity diffusion layer (drain region)

G: gate electrode part

S: impurity diffusion layer (source region)

BL: Bit line

WL: word line

PL: Plate Wire

Embodiments of the present invention will be described below with reference to the drawings.

First, a brief description will be given of a ferroelectric memory (FRAM) as an object of the present invention.

Fig. 9 shows an equivalent circuit of a ferroelectric memory cell of one transistor and one capacitor type. In Fig. 9, C is a ferroelectric capacitor, Q is a MOS transistor for charge transfer, WL is a word line connected to the gate of the MOS transistor, BL is a bit line connected to one end of the MOS transistor, and PL is a The plate line and VPL connected to one end (plate) are plate line voltages.

Fig. 10 shows an equivalent circuit of a part of a ferroelectric memory having, for example, a ferroelectric memory cell array in a bit line repeat configuration.

In Fig. 10, MC is a unit cell in which a ferroelectric capacitor C for information storage using a ferroelectric and an MOS transistor (pass transistor) Q for charge transfer are connected in series to each of the inter-electrode insulating films. Arranged to form the memory cell array 10.

WLi (i = 1, 2, 3, ...) is a plurality of word lines commonly connected to the gates of the transistors Q of the unit cells of the same row in the memory cell array 10.

PLi (i = 1, 2, 3, ...) is a plurality of plate lines connected in common to the plates of the capacitors C of the unit cells in the same row in the memory cell array 10.

BLi (i = 1, 2, 3, 4, ...) is a bit line commonly connected to one end of transistors of the unit cells of the same column in the memory cell array 10.

The word line selection circuit 81 selects a part of the plurality of word lines WLi based on the address signal to supply word line voltages.

The capacitor plate line selection circuit 82 selects a part of the plurality of plate lines PLi based on the address signal and controls the voltage of the plate lines PLi.

In addition, a ferroelectric memory cell of a two-transistor and two-capacitor type using two memory cells of Fig. 9 is also known. As shown in Fig. 11 or 12, the two-transistor, two-capacitor-type ferroelectric memory cell has a first transistor Q1 and a second transistor Q2, and the first transistor Q1 and the second transistor. The first capacitor C1 and the second capacitor C2 are connected in series to correspond to the transistor Q2, respectively.

The first bit line BL1 and the second bit line / BL1 are connected to one end (drain) of the first transistor Q1 and the second transistor Q2 and are common to the respective gates. The word line WL is connected, and the plate line PL is connected in common to the plates of the first capacitor C1 and the second capacitor C2.

The word line WL and the plate line PL are provided in parallel, and a word line signal is supplied to the word line WL selected by the row decoder (not shown) for the word line, and the row decoder for the plate line. The plate line voltage VPL is supplied to the plate line PL selected by (not shown).

Further, a sense amplifier (not shown), a write circuit (not shown), and a precharge circuit (not shown) for bit line potential sense amplification are connected to the two bit lines BL1 and / BL1. .

Next, the principle of the data writing operation and the principle of the data reading operation of the ferroelectric memory cell having the two transistor / two capacitor configuration will be described with reference to FIGS. 11 to 13.

11A to 11C show the state of the applied electric field and the electrical polarization of the ferroelectric capacitor in the write operation, and FIGS. 12A to 12C show the state of the applied electric field and the electric polarization of the ferroelectric capacitor in the read operation.

Fig. 13 also shows the potential of the plate line applied during data write and read operations. When writing or reading data to the ferroelectric memory cell, the direction of the dielectric polarization is controlled by changing the potential of the plate line PL of the selected memory cell to, for example, 0V → 5V → 0V.

(A) In the data write operation, in the initial state, the plate line PL is set to the ground potential Vss (0V), and the two bit lines BL1 and / BL1 are precharged to 0V, respectively.

First, as shown in FIG. 11A, one of the two bit lines BL1 and / BL1 (for example, the second bit line / BL1) is set to 5V, for example, and 5V is set in the word line WL. When the two transistors Q1 and Q2 are turned on to generate a potential difference between both ends of the second capacitor C2, for example, downward polarization occurs in the figure, but the polarization of the first capacitor C1 Does not occur.

Next, as shown in FIG. 11B, when the plate line PL is set to 5 V, a potential difference occurs between both ends of the first capacitor C1, and an upward polarization occurs in the figure, but the second capacitor C2 is generated. Polarization is not reversed. As a result, as shown in the two capacitors C1 and C2, polarizations in opposite directions have occurred, and this state corresponds to the recording state of data ″ 1 ″ or ″ 0 ″.

Next, as shown in Fig. 11C, the plate line PL is set to 0 V and the word line WL is 0 V to turn off the two transistors Q1 and Q2.

(B) In the data read operation, in the initial state, the plate line PL is set to 0V, and the two bit lines BL1 and / BL1 are precharged to 0V, respectively. It is assumed here that two capacitors C1 and C2 record data in a state where polarization in the opposite direction occurs as shown in Fig. 12A, for example.

First, as shown in FIG. 12B, when the plate line PL is set to 5V, and for example, 5V is applied to the word line WL, the two transistors Q1 and Q2 are turned on. A potential difference occurs between both ends of the capacitor C2, and the direction of polarization is reversed, but the direction of polarization of the first capacitor C1 is not reversed. The read potentials from these two capacitors C1 and C2 are sense amplified by a sense amplifier, and by the output of this sense amplifier, the two bit lines BL1 and / BL1 are correspondingly set to 0V and 5V. ″ 1 ″ and ″ 0 ″ of read data are determined based on the output of the sense amplifier.

Subsequently, as shown in FIG. 12C, when the plate line PL is set to 0 V, a potential difference occurs between both ends of the second capacitor C2, and the direction of the polarization is reversed, thereby polarizing the first capacitor C1. The direction of does not reverse and returns to the initial state.

Next, an embodiment in which the present invention is applied to the above-described FRAM will be described in detail. 1 to 3 schematically show an example of a planar pattern of a part of the cell array in the manufacturing process sequence of the cell array with respect to the large-capacity ferroelectric memory employing the ferroelectric memory cell according to the first embodiment of the present invention. .

4 to 7 schematically show a part of the cross-sectional structure in the manufacturing process sequence of the cell array, and specifically, illustrates a cross-sectional structure including the SDG region and the cell capacitor along the line A-A in FIG.

First, the structure of the cell array will be described. In the structure shown in Fig. 7, the connection structure between the fast transistor and the upper electrode 19 of the ferroelectric capacitor and the structure of the upper electrode 19 are different from those of the bit line preformed and upper electrode connection structure of the conventional example described above.

In this case, one transistor comprising a structure in which one MOS transistor (pass transistor) for charge transfer and one ferroelectric capacitor for information storage is connected in series is used as a unit cell, and the unit cells are arranged in a matrix to form a memory cell array. A description will be given by taking an FRAM including a one capacitor type ferroelectric memory cell as an example. In addition, for simplicity of explanation, each word line is represented by WL, each bit line is BL, and each plate line is represented by PL.

In Fig. 7, 1 is a semiconductor substrate (e.g., silicon substrate) of a first conductivity type (e.g., p-type), and a plurality of element regions (activation regions) SDG are respectively formed in the surface layer portion thereof, as shown in Fig. 1; It is formed almost linearly in a direction orthogonal to the direction of forming the word line WL (a direction parallel to the direction of forming the bit line BL), and is formed in a matrix-like arrangement in plan view. An oxide film 2 is formed in the isolation region between elements.

Here, the element regions SDG of each column are shifted in position by one length (1 pitch) of the element region SDG for each column, and each element region SDG has a checkerboard arrangement (plus grid) as a whole. Zigzag arrangement).

In each of the element regions SDG, a first drain channel source region constituting the first MOS transistor is formed in a straight line from the center portion to one end region, and forms a second MOS transistor in the other end region from the center portion. The second drain channel source region is formed in a straight line, and the center portion is a drain region D common to the first and second MOS transistors.

The gate electrode portion G is formed on the channel region of the MOS transistor through the gate oxide film 3, and the gate electrode portions G of the plurality of MOS transistors in the same row are successively formed as the word line WL. The word line WL groups are formed in parallel with each other.

In this case, each word line WL (gate electrode portion G) has a two-layer structure of, for example, P-doped polysilicon 4 and WSi (tungsten silicide) 5, and the surface insulating film 6 And sidewall insulating film 7.

Further, an interlayer insulating film 9 and an interlayer insulating film 10 for surface planarization are formed on the surface insulating film 6 and the sidewall insulating film 7, and the word line WL group is formed on the interlayer insulating film 10. The bit line BL group is formed in the direction orthogonal to the formation direction of each.

In this case, a contact hole is opened in the interlayer insulating film 10 corresponding to the impurity diffusion region (drain region) D of the second conductivity type (n type in this example) in each central portion of the element region SDG. And a bit line BL made of a barrier metal film 11 and a conductive film 12 is formed at a position slightly away from the contact hole on the interlayer insulating film 10, and each bit line BL is formed in the contact hole. Contacts each drain region D of a plurality of device regions SDG in the same column.

4 to 7, the bit line BL is indicated by a solid line only in the contact hole, and is indicated by a dotted line on the interlayer insulating film 10 located behind the cross section shown.

In addition, an interlayer insulating film 13 and a cap insulating film 16 for surface planarization are formed on the bit line BL group. On the cap insulating film 16, a ferroelectric capacitor (lower electrode 17, Ferroelectric insulating film 18 and upper electrode 19] are formed, and an insulating film 20 and a passivation film 23 for capacitor protection are formed.

In this case, each of the lower electrodes 17 of the plurality of ferroelectric capacitors in the same row covers the center portion of the SDG region including the corresponding MOS transistor or the upper side of the adjacent interlayer isolation oxide film 2, and the word line WL ) Is formed continuously in the direction parallel to the forming direction of the group (that is, in the direction orthogonal to the bit line BL), and becomes the capacitor plate line PL.

In addition, the upper electrode 19 of the ferroelectric capacitor for each unit cell is formed in, for example, a quadrangle through the ferroelectric insulating film 18 on the corresponding lower electrode 17 region.

The upper electrode 19 of the ferroelectric capacitor connects the electrode wiring 22 for local connection to the impurity diffusion region (source region) S of the second conductivity type (n type in this example) of one end of the corresponding MOS transistor. Connected via

In this case, the interlayer insulating film 13 for surface planarization, the interlayer insulating film 10 for surface planarization, the interlayer insulating film 9, and the like are contacted on the source region S at both ends of the element region SDG. The hole is opened, and a conductive plug (capacitor contact plug) 15 is embedded in the contact hole. In addition, a contact hole is opened in the cap insulating film 16 corresponding to the capacitor contact plug 15, on the inner surface of the contact hole, the insulating film 20 for the capacitor protective film, and the upper electrode 19. For example, aluminum-based wiring is formed as the electrode wiring 22 for local connection.

In this embodiment, the capacitor contact plugs 15 and the electrode wirings 22 are also provided with barrier metal films 14 and 21 on their undersides, similarly to the bit lines BL.

In this example, the capacitor contact plug 15 and the electrode wiring 22 are different in their respective materials. Specifically, the material of the capacitor contact plug 15 is preferably a high melting point metal, and the material of the electrode wiring 22 is preferably an aluminum wiring material, a copper wiring material, or a conductive polysilicon wiring material.

The lower end surface of the electrode wiring 22 has a larger area than the upper end surface of the capacitor contact plug 15, and an interlayer insulating film (in this example, an interlayer insulating film) around the upper surface of the capacitor contact plug 15. 13)]. As a result, the contact resistance between the electrode wiring 22 and the capacitor contact plug 15 can be reduced, and the margin of mask alignment can be secured when opening the contact hole corresponding to the capacitor contact plug 15. have.

Next, the manufacturing method of the said cell array is demonstrated in order of a process with reference to the flat pattern shown in FIGS. 1-3 and sectional drawing shown in FIGS.

First, as shown in Figs. 1 and 4, an array of MOS transistors of cells is formed on the silicon substrate 1 by the same process as that of forming a conventional CMOS DRAM cell.

Wherein 2 is an oxide film (D, S) forming an element isolation region selectively formed in the substrate surface layer portion is a drain source region consisting of a reverse diffusion impurity diffusion layer and a substrate selectively formed in the element formation region of the substrate surface layer portion, 3 is the substrate surface The gate oxide film and G for the MOS transistor formed in the gate electrode portion (part of the word line WL) for the MOS transistor formed on the gate oxide film 3.

Next, an interlayer insulating film 10 is formed on the substrate including the gate electrode portion G, and contact holes are formed in corresponding portions on the drain region D of the interlayer insulating film 10. In addition, the barrier metal film 11 and the conductive film 12 are sequentially formed on the inside of the contact hole and the interlayer insulating film 10, and the conductive film 12 and the barrier metal film 11 on the interlayer insulating film 10 are sequentially formed. The bit line BL is formed by patterning.

Next, an interlayer insulating film 13 for planarization is deposited on the substrate including the bit line on the order of 800 nm, and then planarized by polishing about 200 nm by chemical mechanical polishing (CMP).

Next, as shown in FIG. 5, an opening of, for example, 0.8 x 0.8 mu m square in a portion corresponding to the source region S of the interlayer insulating film 13 and the interlayer insulating film 10 by a lithography process and an etching process. Contact holes for capacitor plugs having an area are selectively formed. In this case, the total insulating film thickness of the interlayer insulating film 13 and the interlayer insulating film 10 is 1500 nm, and the aspect ratio of the opening is 1.9.

Further, after depositing a barrier metal film (for example, a TiN film) 14 by 20 nm on the inner surface of the contact hole, tungsten is deposited by about 1700 nm, which is equal to or greater than the total thickness of the insulating film, by a metal CVD apparatus, for example. To be reclaimed entirely.

Thereafter, by removing the tungsten film and the barrier metal film on the planarization interlayer insulating film 13 by etching back, the capacitor contact plug 15 can be obtained as shown in FIG.

In addition, since the barrier metal film 14 is formed on the inner wall of the contact hole when the capacitor contact plug 15 is embedded, it is possible to prevent diffusion from the contact plug 15 into the impurity diffusion layer for the source region S.

Further, as shown in FIG. 5, after the surface of the interlayer insulating film 13 is sufficiently flattened by CMP, the insulating film for cap 16 is deposited by 150 nm.

Next, as shown in FIGS. 2 and 6, the conductive film for the capacitor lower electrode 17 (capacitor plate line PL) and the ferroelectric film 18 for the capacitor insulating film are sequentially formed on the cap insulating film 16. The capacitor upper electrode 19 is formed, the ferroelectric film 18 and the conductive films for the lower electrode 17 are patterned to form the ferroelectric capacitor, and then the capacitor protective insulating film 20 is formed. At this time, Pt or the like is used as the capacitor lower electrode 17 or the capacitor upper electrode 19 such as a PZT (PbZr _X Ti _1-X O ₃ ) film or an SBT (SrBi ₂ Ta ₂ O ₉ ) film as the ferroelectric film 18. It is available.

Next, a portion corresponding to the capacitor contact plug 15 of the capacitor protective insulating film 20 and the cap insulating film 16 is opened, and a portion corresponding to the capacitor upper electrode 19 of the capacitor protective insulating film 20. To open. In this case, an opening (in FIG. 2, 16a) larger than the area of the upper end of the capacitor contact plug 15 and an opening (in FIG. 2, 19a) smaller than the area of the capacitor upper electrode 19 are formed.

3 and 7, as the electrode wiring material for connecting the capacitor contact plug 15 and the capacitor upper electrode 19, for example, the TiN film 21 and Si · Cu for a barrier metal film. A conductive film such as an Al (aluminum) wiring containing a (silicon / copper) component is deposited in order by, for example, a high frequency sputtering method, a metal CVD method, or a MOCVD method so as to cover the capacitor protective insulating film 20, and patterning this. The electrode wirings 22 are formed, and the passivation film 23 is deposited thereon.

In the formation of the ferroelectric film 18, after the deposition of the ferroelectric material, in order to crystallize the ferroelectric material and to enhance the ferroelectric properties, a high-temperature heat treatment is usually performed for about 10 seconds in a high temperature oxygen atmosphere of about 750 ° C.

Furthermore, in order to recover the fall of the ferroelectric property which arises when capacitor patterning is performed in the process after deposition of a ferroelectric material, annealing is performed for about 30 minutes in 600 degreeC high temperature oxygen atmosphere.

In the cap insulating film 16 during the treatment in the high temperature oxygen atmosphere, the contact hole for forming the electrode wiring is not opened until the thermal treatment process of the ferroelectric material when the ferroelectric film 18 is formed is completed. It has a function which prevents oxidation of a capacitor contact plug material.

However, even when the capacitor contact plug 15 is covered with the cap insulating film 16, it is inevitable that the surface of the capacitor contact plug material is partially oxidized to a light extent by annealing to a high temperature oxygen atmosphere.

Thus, preferably, when depositing the electrode wiring material on the capacitor contact plug 15, a process of etching the surface oxide film of the capacitor contact plug 15 beforehand is added to the capacitor contact plug 15 and the electrode wiring material. Stable connection is possible. Etching at this time can be made into a reverse sputter | spatter by replacing the electrode of a normal metal sputter | spatter.

In addition, the sintering process at 450 DEG C using a mixed gas of hydrogen and nitrogen, which is generally performed to lower the contact resistance between the MOSFET active layer and the contact plug, cannot be used for the reason of deteriorating the characteristics of the ferroelectric capacitor in the conventional process example. . On the other hand, according to the manufacturing method of the above embodiment, by manufacturing the capacitor contact plug 15 before the formation of the ferroelectric capacitor, the same sintering process as that of the normal MOS type LSI can be adopted before the formation of the ferroelectric capacitor. It becomes possible to sinter about 400 to 500 degreeC using hydrogen or nitrogen or these mixed gases. As a result, there is an advantage in that various device parameters such as the gate threshold Vth of the MOSFET and the substrate potential can be controlled in common.

In addition, in the manufacturing method of the embodiment, as the material of the capacitor contact plug 15, the same material as that of the electrode wiring is used, and a material having oxidation resistance, heat resistance, low contact resistance, and filling into a high aspect ratio contact hole is used. Although this is preferable, the use of high melting metals, such as tungsten, molybdenum, titanium, palladium, is preferable, for example.

This is because when a material which is easily oxidized such as a polysilicon material or an aluminum-based material is used as the capacitor contact plug 15, the high temperature heat treatment in an oxygen atmosphere is performed when the ferroelectric capacitor is manufactured after the capacitor contact plug 15 is buried. This is because the capacitor contact plug 15 is also applied to the capacitor contact plug 15 and the capacitor contact plug 15 is oxidized to increase the parasitic resistance.

In this embodiment, TiN is used as an interlayer between the AlSiCu electrode wiring material and the tungsten contact plug material. However, a laminated film of Ti / TiN may be used. As the electrode wiring material, it is possible to use not only AlSiCu wiring but also aluminum and copper wiring materials or conductive polysilicon wiring materials.

Further, in the manufacturing method of the above embodiment, in order to reduce the contact resistance between the contact plug for the capacitor and the electrode wiring material, the connection structure in which the electrode wiring has a wiring area larger than the area of the upper end surface of the contact plug for the capacitor in these contact surfaces. It is adopted. In other words, in this example, the electrode wiring AlSiCu / TiN on the capacitor contact plug is in contact with both the upper surface of the contact plug W and the peripheral insulating film (interlayer insulating film 13 in this example).

Next, use Pt or other electrode materials (Ir, Ir oxide, Ru oxide, etc.) as the upper electrode material of the ferroelectric capacitor using the PZT material or the SBT material as described above, and fine the upper electrode of the ferroelectric capacitor to 0.1 micron level. It will be described with reference to Figs. 8A to 8F. In addition, this process is applicable also at the time of formation other than the electrode for ferroelectric capacitors.

First, as shown in FIG. 8A, the lower electrode film 17a and the ferroelectric thin film 18a of the ferroelectric capacitor are sequentially deposited on the cap insulating film 16. In this case, 175 nm Pt is formed as the lower electrode film 17a, and 300 nm PZT film is formed as the ferroelectric thin film 18a.

Next, as shown in FIG. 8B, a 300 nm TEOS (tetraethoxysilane) oxide film 20a is deposited on the ferroelectric thin film 18a.

Next, as shown in FIG. 8C, an opening corresponding to the desired upper electrode area is selectively formed in the TEOS oxide film 20a by using a PEP (photo etching process).

Next, as shown in FIG. 8D, the Pt film 19a for forming the upper electrode is deposited more than the film thickness of the TEOS oxide film 20a.

Next, as shown in Fig. 8E, the Pt film 19a on the TEOS oxide film 20a is removed by etching back or CMP. The TEOS oxide film 20a / ferroelectric thin film 18a / lower electrode film 17a is formed by anisotropic etching using a photolithography technique to form a strip-shaped resist pattern and using the resist pattern as a mask. Patterning sequentially.

As a result, a desired strip-shaped ferroelectric thin film 18 and a lower electrode 17 are obtained. At this time, the TEOS oxide film 20a, the ferroelectric thin film 18a, and the lower electrode film 17a are sequentially etched using the same master pattern, so that the TEOS oxide film 20a, the ferroelectric thin film 18, and the lower part are self-aligned. The electrode film 17 is formed in substantially the same planar shape.

Next, as shown in FIG. 8F, processing losses due to anisotropic etching at the pattern edges of the ferroelectric thin film 18 and the lower electrode 17 are alleviated, and the electrical insulation breakdown voltage of the ferroelectric thin film 18 is lowered. In order to suppress the etc, the capacitor protection insulating film 20 is formed so as to cover the surfaces of the TEOS oxide film 20a, the upper electrode 19, the ferroelectric thin film 18, and the lower electrode 17. As the capacitor protection insulating film 20, for example, SiO ₂ film formed by a SiO ₂ film, or a thermal oxidation method by decomposition of TEOS by a plasma CVD method.

Then, an opening smaller than the area of the upper electrode 19 is provided in a portion corresponding to the upper electrode 19 of the capacitor protective insulating film 20, and then the electrode wiring 22 and the passivation film for final protection as described above. (23) is formed.

As described above, in the method of manufacturing the ferroelectric memory cell, a ferroelectric capacitor is formed after embedding a contact plug layer on one end region of the fast transistor, and connecting the upper portion of the capacitor upper electrode and the contact plug. It is possible to form the electrode wiring by, for example, a sputtering method.

Thereby, the wiring film deposition process in a reducing atmosphere using a metal CVD apparatus or a MOCVD apparatus after formation of the ferroelectric memory cell can be avoided, and deterioration of electrical characteristics such as the amount of residual polarization of the capacitor can be prevented.

Further, since the capacitor upper electrode 19 is embedded in the opening of the insulating film 20a, the area of the capacitor upper electrode 19 can be reduced, the area of the unit cell can be reduced, and the FRAM can be highly integrated.

Next, an example in which the above-described FRAM is applied to an RFID (Radio Frequency Identication) system is shown.

The RFID system refers to a non-contact type tag system (identifier) using radio waves, and is generally called a non-contact data carrier system or the like. The overall system configuration of the RFID system is shown in FIG.

The RFID system is composed of a host side composed of a personal computer, a controller, an antenna and the like and a data carrier called a transponder. The transponder is a simple configuration with a monolithic RFID chip in which FRAM and ASIC are integrated into one chip, and an antenna that serves as power reception and data reception / transmission.

On the host side, commands and data are carried on the carrier as necessary, and the transponder side generates power required by the carrier, and returns information to the host side for use in recording, reading, and transmitting data.

A contactless tag requires no battery and can be utilized for management of people's in and out by reading the contents of the FRAM non-contact using radio waves and rewriting the contents. For example, you don't have to stop to open a ticket with a contactless tag for a commuter pass in the pocket of your clothes, or run with a contactless tag attached to your car to settle at a tollgate on a freeway, or enter and exit a parking lot without intervening with a person. It is aimed at the purpose of monitoring and managing the data. It can also be used to manage the behavior of livestock or ponies.

15 shows a detailed internal circuit of the transponder.

That is, the LC circuit for detecting electromagnetic waves input from the outside, the circuit 58 for generating a signal from the electromagnetic waves detected by the LC circuit, the circuit 59 for generating a power supply voltage from the electromagnetic waves detected by the LC circuit, The power-on circuit 60 for detecting the rise and outputting the power-on signal, the ferroelectric capacitor having the ferroelectric material in the electrode, and the MOS transistor for charge transfer are arranged in a plurality of matrix types, for example, the same. The MOS transistors of the memory cells belonging to the row are commonly connected by the same word line, and the one electrode of the ferroelectric capacitors of the memory cells belonging to the same row are commonly connected by the same capacitor plate line, respectively, and the MOS transistors of the memory cells belonging to the same column are Consisting of an FRAM cell array 61 and the like, each terminal connected in common with the same bit line .

In addition, the present invention is not limited to the FRAM described above, but applied to a method of forming a ferroelectric memory cell, which is used in a small amount of logic in a program storage portion of a logic in a logic LSI equipped with an FPGA (Field Programle Gate Array) or static RAM. It is also possible.

In addition, the present invention is not limited to the case where the ferroelectric memory cell is formed on the semiconductor substrate as described above, but can also be applied to the case where the ferroelectric memory cell is formed on the semiconductor layer on the insulating substrate such as SOI.

As described above, according to the manufacturing method of the semiconductor device of the present invention, when forming a ferroelectric memory cell, a ferroelectric capacitor is formed after embedding a contact plug layer on one side region of a fast transistor, and forming a capacitor upper electrode and a contact plug. Since the upper end portion is connected by electrode wiring, the influence of the treatment in the reducing atmosphere after the formation of the ferroelectric capacitor can be avoided, and the ferroelectric capacitor can be easily formed.

In addition, according to the manufacturing method of the semiconductor device of the present invention, it is possible to realize the fine processing of the capacitor upper electrode (Pt, etc.), and further refine the pattern of the ferroelectric memory cell.

Therefore, according to the semiconductor device manufactured by the manufacturing method of the semiconductor device of the present invention, it is possible to have a structure capable of miniaturizing the ferroelectric capacitor because the reliability of the electrode wiring for connecting the capacitor upper electrode and the upper end of the contact plug is high.

Claims (16)

Forming a MOS transistor having a drain region and a source region composed of an impurity diffusion region in the surface layer portion of the semiconductor substrate; Thereafter, forming a first insulating film on the semiconductor substrate; Forming a bit line on the first insulating film, the bit line of which a lower end contacts a region on one end of the MOS transistor; Forming a second insulating film on the bit line and on the first insulating film; Selectively opening a contact hole in the second insulating film and the first insulating film, and forming a capacitor contact plug having a lower end contacting the other end region of the MOS transistor; Thereafter, forming a ferroelectric capacitor having a lower electrode, an inter-electrode insulating film using a ferroelectric material, and an upper electrode on the semiconductor substrate; Forming an electrode wiring connecting the upper electrode of the ferroelectric capacitor and the upper surface of the capacitor contact plug; Provided with Depositing a third insulating film on the semiconductor substrate between the step of filling the capacitor contact plug and the step of forming the ferroelectric capacitor; A step of opening a contact hole for an electrode wiring contact in the third insulating film between the step of forming the ferroelectric capacitor and the step of forming the electrode wiring; It further comprises a manufacturing method of a semiconductor device. The method of claim 1, The step of forming the electrode wiring is a method of manufacturing a semiconductor device, characterized in that the electrode wiring material is deposited and patterned after etching the upper surface of the capacitor contact plug. The method of claim 1, And a step of sintering using at least one of a hydrogen gas and a nitrogen gas between the step of embedding the capacitor contact plug and the step of forming the ferroelectric capacitor. The method of claim 1, When forming the ferroelectric capacitor, after depositing a lower electrode film and an inter-electrode insulating film, the third insulating film is deposited on the inter-electrode insulating film, the third insulating film is selectively opened, the openings and the third insulating film. And depositing the electrode material for forming the upper electrode on the upper electrode, and then removing the electrode material on the third insulating film by etching back or chemical mechanical polishing to form the upper electrode. The method of claim 4, wherein And after removing the electrode material on the third insulating film, the third insulating film, the inter-electrode insulating film, and the lower electrode film are sequentially patterned by using the same master pattern. The method of claim 1, The process of forming the capacitor contact plug may be performed on the second insulating film after opening the contact hole and the inside of the contact hole by depositing a high melting point metal material using a metal CVD method or a MOCVD method, followed by chemical mechanical polishing. A high melting point metal material on an insulating film is removed. A plurality of memory cells each having a ferroelectric capacitor for information storage and an MOS transistor for charge transfer using a ferroelectric material in an inter-electrode insulating film, and a plurality of commonly connected to gates of the MOS transistors of the memory cells in the same row, respectively. A ferroelectric memory having a word line, a plurality of capacitor plate lines commonly connected to ferroelectric capacitors of the memory cells in the same row, and a plurality of bit lines commonly connected to one end of the MOS transistors of the memory cells in the same column, respectively. In the method for producing At the predetermined position of the surface layer portion of the semiconductor substrate, two drain, channel, and source regions constituting the MOS transistors are formed in a straight line while sharing the drain region at the central portion, respectively, in a direction substantially parallel to the bit line direction. A process of determining the cell array region by regularly arranging the channel and source regions in a regular grid shape; A plurality of word lines having gate electrode portions stacked on the channel regions of the respective MOS transistors in the plurality of drain channel and source regions in the same row of the cell array region through a gate insulating film in a direction substantially parallel to each other. Forming process, Forming a first insulating film on the word line; A plurality of bit lines contacting common drain regions in a plurality of drain channel and source regions in the same column of the cell array region are substantially parallel to each other on the first insulating film or in the plurality of word lines. Forming in an orthogonal direction, Forming a second insulating film on the bit line and on the first insulating film; Forming a capacitor contact plug having a lower end contacting the source region in the drain channel source region in the second insulating film and the first insulating film; Forming a third insulating film for a cap on the capacitor contact plug and on the second insulating film; On the third insulating film, a plurality of capacitor plate lines serving as lower electrodes shared by ferroelectric capacitors in a plurality of memory cells of the same row are formed in a direction substantially parallel to the word lines, Forming a plurality of ferroelectric capacitors having the lower electrode, an inter-electrode insulating film using a ferroelectric material, and an upper electrode corresponding to each unit cell; Forming a fourth insulating film for protecting a surface of the ferroelectric capacitor; A portion corresponding to the capacitor contact plug of the fourth insulating film and the third insulating film, while opening the first contact hole for connecting the electrode wiring to a portion corresponding to the upper electrode of the ferroelectric capacitor of the fourth insulating film. Opening a second contact hole for electrode wiring connection in the Depositing an electrode wiring material on the fourth insulating film, and patterning and forming electrode wiring for connecting the upper electrode of the ferroelectric capacitor and the upper surface of the capacitor contact plug for each unit cell; A method for manufacturing a semiconductor device, comprising: The method of claim 7, wherein The step of filling the capacitor contact plug may include: selectively opening a contact hole in the second insulating film and the first insulating film, depositing a high melting point metal material on the second insulating film and in the contact hole; And removing the high melting point metal material on the second insulating film by chemical mechanical polishing. A MOS transistor having a drain region and a source region formed of an impurity diffusion region formed in the surface layer portion of the semiconductor substrate; A first insulating film formed on the MOS transistor; A capacitor contact plug formed in the first insulating film and having a lower end contacting one of the drain region and the source region; A ferroelectric capacitor formed on an upper layer side of the first insulating film, the ferroelectric capacitor having a lower electrode, an inter-electrode insulating film using a ferroelectric material, and an upper electrode; An electrode wiring connecting an upper end of the capacitor contact plug and an upper electrode of the ferroelectric capacitor Provided with And a second insulating film interposed between the first insulating film and a lower electrode of the ferroelectric capacitor. The method of claim 9, Wherein the capacitor contact plug and the electrode wiring are different in their respective materials. The method of claim 10, The material of the capacitor contact plug is a high melting point metal, and the material of the electrode wiring is at least one selected from an aluminum-based material, a copper-based material, and a polysilicon-based material. The method of claim 9, The area of the bottom surface of the said electrode wiring is larger than the area of the top surface of the said contact plug, and the bottom surface of the said electrode wiring is contacted on the top surface of the said capacitor contact plug, and on the said 1st insulating film. The method of claim 9, And the upper electrode of the ferroelectric capacitor is formed by embedding Pt in the upper electrode embedding insulating film deposited on the inter-electrode insulating film of the ferroelectric capacitor. The method of claim 9, And a wiring layer having a lower end contacting the other region of the drain region and the source region in the first insulating film. The method of claim 9, Two drain channel source regions sharing a drain region in the central portion are regularly arranged in a plurality of checkerboard shapes at the surface layer portion of the semiconductor substrate, constituting the MOS transistors, respectively, and above and closest to the drain channel source region. A semiconductor device, wherein the ferroelectric capacitor is disposed above each of the two drain channel source regions to form a cell array region. The method of claim 9, A plurality of memory cells each having a ferroelectric capacitor for information storage and an MOS transistor for charge transfer using a ferroelectric material in an inter-electrode insulating film, and a plurality of commonly connected to gates of the MOS transistors of the memory cells in the same row, respectively. A ferroelectric memory having a word line, a plurality of capacitor plate lines commonly connected to ferroelectric capacitors of the memory cells in the same row, and a plurality of bit lines commonly connected to one end of the MOS transistors of the memory cells in the same column, respectively. It is a semiconductor device characterized by the above-mentioned.

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