JP3120380B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a structure of an electrically rewritable nonvolatile memory using a ferroelectric material.

[0002]

2. Description of the Related Art Conventional semiconductor nonvolatile memories include:
Although MIS type transistors are generally used and put to practical use as EPROM (ultraviolet erasing nonvolatile memory) and EEPROM (electrically rewritable nonvolatile memory), they have a high rewriting voltage of about 20 V and a high rewriting time. The problem is that it is long. Therefore, recently, there has been proposed a nonvolatile memory that uses a ferroelectric film that can electrically invert the polarization, and in which the write time and the read time are almost the same in principle and the polarization is maintained even when the power is turned off. I have. For a nonvolatile memory using such a ferroelectric film, for example, a structure in which a capacitor made of a ferroelectric film is integrated on a silicon substrate as described in U.S. Pat.
There is a non-volatile memory in which a ferroelectric film is arranged at the gate portion of a type transistor or a structure in which a ferroelectric film is laminated on a MOS type semiconductor device as in IEDM: 87 pp, 850-851. However, no satisfactory products have been obtained in terms of integration and manufacturing process.

FIG. 2 shows an example of a conventional semiconductor device.
The second field 208 is deposited through the semiconductor substrate 201, the LOCOS 202, the gate film 203, the polysilicon electrode 204, the low concentration diffusion layer 205, the side wall film 206, and the high concentration diffusion layer 207. After contact photoetch, 209 barrier metal and 210 AL
A system alloy wiring is formed. Subsequently, the Pt lower electrode 211 and PZT (PbTiO ₃ / PbZrO ₃ ) 212 are formed by sputtering.
Then, a Pt upper electrode 213 is deposited and a ferroelectric memory film is formed by patterning. After annealing in O ₂ , depositing the CVD oxide film 214, performing contact photoetching to form a barrier metal 215 and an Al-based wiring 216, and forming a passivation film 217 to complete the process.

[0004]

However, in the conventional method,
PZT and PLZT are formed by the sputtering method, and the crystallinity is poor. Therefore, a heat treatment at 500 ° C. or more in O ₂ is required. At this time, since the barrier property between Al and PZT or Si is not sufficient, the contact portion is not formed. Leakage or characteristic deterioration. The switching characteristics of the PZT, the hysteresis characteristic has a problem that greatly reduced with H ₂ treatment.

An object of the present invention is to provide a semiconductor device in which a ferroelectric memory with a high yield and a high reliability is integrated without reducing the degree of integration while eliminating such problems. I have.

[0006]

According to the present invention, there is provided a semiconductor device comprising:
In a semiconductor device in which a ferroelectric material is disposed on a semiconductor substrate, the semiconductor device includes a pair of electrodes provided so as to sandwich the ferroelectric material, and at least one of the electrodes includes a metal plating layer and the metal plating. An electroless metal plating layer having a material different from that of the metal plating layer is formed on the layer.

[0007]

The reaction with Si or PZT can be prevented by not using an AL-based material for the upper and lower electrodes or the wiring. Furthermore, in addition to obtaining very good coverage by plating, spatter damage and H _{2 for} recovery can be obtained.
The monitor becomes unnecessary.

[0008]

FIG. 1 shows an embodiment of the present invention. 101 is a semiconductor substrate, 102 is LOCOS, 103
Is a gate film, 104 is a polysilicon electrode, 105 is Mo.
SiX, 106 is a low concentration diffusion layer, 107 is a side wall film, 108 is a high concentration diffusion layer, and 109 is a second field film. After contact etching, a barrier metal 110 is formed. First, the barrier metal is made of a TiN / Ti layer of 100
Pt / Ti is formed by 0 ° / 200 ° sputtering for 30 seconds in O ₂ plasma to improve the barrier property.
Then, a pattern other than the wiring portion is formed with a resist, the Au plating wiring 111 is formed by electroplating of 1.0 μm, the resist is removed, and the barrier layer is etched by ion sealing using the Au plating layer as a mask. Next, Ru112 is electrolessly plated at 800.degree.
Oxidation is performed at 00 ° C. to 800 ° C. to form a RuO ₂ 113 layer having a thickness of several hundred Å. Subsequently, PZT3000 # 114 and Pt115 of the upper electrode are applied by sputtering, and a ferroelectric is formed in a predetermined pattern by photoetching. Next, plasma TEO
After 1.0 μm of S film 116 and 0.4 μm of thermal TEOS film were etched back by RIE and flattened,
G is spin-coated at 1000 ° and annealed at 500 ° C.
Further, the SOG on the plane portion is etched back with Ar and C ₂ F ₆ -based gas, and then holes are formed to form upper wiring. Pt / Ti117 is used as a barrier metal, and as a wiring,
Au plating 118 was used. Ru electroless plating was used on the Au plating in the same manner as the lower electrode wiring. For the passivation, a plasma TEOS film 119 was used.

[0009]

According to the present invention, in order to improve the ferroelectric switching and systemic characteristics of PZT, annealing in O ₂ at 500 to 700 ° C. is required. It was good without any change. Further, there was no reaction between PZT and RuO ₂ / Ru / Au, and no deterioration in characteristics. In addition, although the adhesion between Au and SiO ₂ is very poor in the past, the adhesion of the present invention was greatly improved by the method of the present invention, and the use of a SiO ₂ film became possible.
This is because it is not necessary to use a plasma nitride film etc.
In addition to avoiding the influence of H ₂ , which causes PZT characteristic degradation, the nitride film having a high dielectric constant can be made thicker with a low oxide film, which is effective in reducing the interlayer capacitance. In addition, RuO
₂ serves as a substitute for the conventional lower Pt electrode, so that it is also rationalized. Further, the plating wiring eliminates the sputtering damage on H ₂ monitors for recovery is also unnecessary, coverage is good, and wipe the drawbacks of conventional AL system interconnect, an integrated circuit technology which has a ferroelectric It is an indispensable method.

In this embodiment, the plating metal is Au.
, But Cu, Ag, Ni, Co, Pt, Rh, W
The same effect can be obtained by using an electroless plating layer on top of Ru, Ti, Zr, Cr, etc., and by nitriding or boring instead of oxidation, TiN, ZrB _2, etc. The above-described effect is exhibited even if the above is formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor device of the present invention.

FIG. 2 shows a cross-sectional view of a conventional semiconductor device.

[Explanation of symbols]

101, 201: Semiconductor substrate 102, 202: LOCOS 103, 203: Gate film 104, 204: PolySi film 105: MoSiX film 106, 205: Low concentration diffusion Layers 107, 206: Side wall films 108, 207: High concentration diffusion layer 109, 208: Second field film 110, 209: Barrier metal 111: Au plating wiring 112 · · · · · · · Ru electroless plating layer _{113 ······· RuO 2 114,212 ··· PZT 115,213} ··· upper Pt electrode 116,214 ... interlayer SiO ₂ 117,215 ... Barrier metal 118 ... Second layer Au plating wiring 119,217 ... Passivation film 210 ... First AL wiring 11 ....... lower Pt electrode 216 ....... first 2AL wire

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 27/10 H01L 21/8242 H01L 27/108

Claims (1)

(57) [Claims] In a semiconductor device having a ferroelectric material disposed on a semiconductor substrate, the semiconductor device has a pair of electrodes provided so as to sandwich the ferroelectric material, and at least one of the electrodes is formed of metal plating. A semiconductor device comprising an electroless metal plating layer having a material different from that of the metal plating layer formed on the metal plating layer and the metal plating layer.