JPS5814561A - Passive element for trimming - Google Patents

Abstract

PURPOSE:To prevent a trimmer part from breakdown by a method wherein a narrow stripe shaped polycrystalline Si layer is mounted on an oxide film covering a diffused region, subjected to heat treatment for the superficial part thereof to be transformed into SiO2 to work as a mask in a process of providing a window in the oxide film, and an electrode is connected to the diffused region, when an electrode is attached to a diffused region. CONSTITUTION:An N-type semiconductor substrate 101 provided with an N<+> type diffused region 102 is covered with an oxide film 103 and then with a polycrystalline Si layer 104, and is subjected to heat treatment for the conversion of the superficial part of the layer 104 into a thin oxide film 105. Next, the film 105 is subjected to photoetching and, with the film 105 as it is, the layer 104 is subjected to plasma etching, for the formation of a narrow polycrystalline Si stripe 106, in which process the stripe 106 is overetched so that an eaves like narrow oxide film stripe 107 remains of the film 105 to cap the narrow stripe 106. Next, the film 103 on the region 102 is subjected to etching and then to heat treatment, for the formation of a capacitor oxide film 108 and a capacitor trimming oxide film 109 of the same thickness. The film 103 is then provided with a window, and an Al wiring 111 to be an end of the capacitor is attached to the region 102.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to passive elements such as resistors and capacitors that can be easily trimmed.

Trimming methods for resistors, capacitors, etc. include laser trimming and Zener destruction trimming.

There are works by Borislich, -s, etc. Laser trimming and polysilicate use destroy the trimmed part, so
There are reliability problems, laser) IJ trimming and Zener destruction trimming have the disadvantage that they require a certain amount of area for trimming.

SUMMARY OF THE INVENTION An object of the present invention is to provide a passive element that is easy to trim, with no damage to the trimmed portion, and a small area required for trimming.

Trimming according to the invention - 1E4: Fi, - conductivity type (D
a semiconductor substrate, an insulating film formed on the semiconductor substrate, an insulating strip formed on the insulating film whose upper part protrudes like an eave, and an insulating strip formed on the semiconductor substrate below the insulating film. a plurality of wiring electrodes connected to the passive elements formed on the insulating film and drawn out onto the insulating film through windows formed in the insulating H; , and a conductive strip provided so as to create a break at this portion and connect arbitrary wiring electrodes among the wiring electrodes.

Next, the present invention will be explained based on examples.

FIGS. 1(a) and 1(b) are cross-sectional views during the manufacturing process of an M)8 capacitor as an embodiment of the present invention. As shown in FIG. 1 (1), an oxide film 103 is formed on an N-type semiconductor substrate 101 on which an N diffusion layer (not shown) is formed, and a polysilicon film 104 is formed on the oxide film 103.
It is grown to a thickness of about 6000λ. polysilicon 104
Fi is oxidized to form an oxide film 105 of approximately 1000λ on the surface of the polysilicon. Next, as shown in FIG. Polysilicon strips 106' are formed by plasma etching. At this time, the polysilicon 104 is slightly overetched and becomes a polysilicon strip 106, but the oxide film 105 on the polysilicon 104 is on the polyW 13 :I strip 106 and becomes an eaves-shaped oxide film strip. It becomes 107. Next, Figure 1 <
FIGS. 4(d) and 4(e) showing the plan view of C) and the AA and BB cross sections of the same figure, respectively! - Referring to the above, the oxide film 103t on the N+ type scattering layer 102 is etched and then thermally oxidized, and the capacitor oxide film 108. ) A capacitor oxide film 109 for mounting is formed. At this time, the capacitor oxide film 10B and the capacitor oxide film for trimming are simultaneously formed to have the same thickness. Furthermore, in order to make ohmic contact with the N+ type scattering layer 102, an oxide film window is formed in the oxide film 403, and an aluminum wiring 111 is formed to serve as one end of the capacitor.
is formed. Capacitor oxidation 1110g is covered with aluminum electrode 11 & capacitor liquefied film 109 for trimming is covered with aluminum electrode 113, Arun electrode 112 and aluminum electrode 11
3 are aluminum wires 114 and 115 connected to trimming electrodes 116 and 117, respectively. Also, aluminum wiring 114
Aluminum wiring 11 between and aluminum wiring 115
This aluminum wiring 118 is formed in such a way that B is connected to
In order to cross the Fi polysilicon m-strip 106 and the nine-eaves-shaped oxide film 107 formed thereon, a step is created at this portion. Note that the thickness of the aluminum film in the above explanation is approximately 2.
This is OJIm.

MO8 capacitor oxide film 10 completed in this way
However, by applying a voltage of about 10V to the trimming electrodes 116 and 117, the cut portion of the aluminum wiring 1180 becomes a short circuit, and the value of the M08 capacitor is determined by the capacitor oxide film 108. The reason why the 6-step cut portion, which is the determined value plus the value due to the trimming capacitor oxide film, becomes short-circuited when voltage is applied is that when the electric field exceeds a certain critical value, the aluminum conductor spacing at the step-break portion is small. This is because atomic emission occurs and the gaps between aluminum are filled.

Since this film thickness must be determined based on the characteristics of the device, the electric field critical value can be controlled by adjusting the polysilicon film thickness. Polysilicon film thickness is approximately 600mm
At 0λ, the critical voltage value is 4 when the aluminum film thickness is approximately 20 μm.
．． It was 0 to 9.5v.

FIG. 2 (1) is a plan view of a resistor as a trimming electrode as a second embodiment, FIG. In these figures, NW conductor board 201 yen KP type diffused resistor 2
21 is formed, and an oxide film 203t- is formed on the semiconductor substrate 201.
First, polysilicon and oxide films are sequentially grown on the oxide film 203 in the same manner as described in FIG.
Get 09.

Furthermore, in order to completely eliminate ohmic contact with the P-type diffused resistor 221, an oxide film window is formed in the oxide film 203, and these are connected to the Arun wiring 22, which will become one end of the resistor, the Alζ wiring 223, which will become the other end of the resistor, and the resistor. +2)) Peal who becomes a Qt song child. Placement [2z4゜225.226,22
Connected to 7. These aluminum wires 224, 225,
The other ends of 226 and 227 are aluminum electrodes 228 and 2, respectively.
29,230° connected to 231, aluminum arrangement 224,
Between 225° and 226.227, home wiring is 232 and 23.
Although it is said to be connected at 3°234, these aluminum wires 232, 233, 234 are connected to polysilicon strips 208,
Since it crosses the oxide film strip 209, the aluminum wiring is broken at this portion as in FIG.

The resistor completed in this way has an aluminum electrode 228
．． By appropriately selecting two of 229, 230, and 2310 and applying a voltage, seven types of kO resistance values can be obtained. If the critical voltage value for trimming is small, the applications that can be used for It ring are limited, but by increasing the thickness of the polysilicon film, the critical voltage value can be increased, so that it can also be used at high voltages.

In the above manner, a passive element such as a short-circuit mode trimming resistor or capacitor that does not require area can be obtained. Incidentally, in the above explanation, an example was given in which a combination of polysilicon iWI film was used as the conductor part.
Needless to say, this can also be achieved by, for example, a combination of a vapor-grown nitride film and a nitride film.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a cross-sectional view of an MO8 capacitor according to an embodiment of the present invention during the manufacturing process, FIG.
), (e) are A-& and B-B of figure (e), respectively.
A sectional view, FIG. 2(a) is a plan view of the second embodiment of the present invention,
Figures (b) and (Q) are sectional views taken along line A and B in figure (a), respectively. 101.201...N'fJ cow conductor board, 10
2...N+ diffusion layer, 103,203...
・Oxide film, 104°204...Polysilicon,
105,205...Oxide film on polysilicon,
106,206...Polysilicon strip, 107
, 209... Eaves-shaped oxide film strips, 108...
...Capacitor oxide film, 109...00. Capacitor oxide film for trimming, 111... Al (wiring) connected to N diffusion layer, 112... Aluminum electrode covering capacitor oxide film, 113... Capacitor oxide for trimming Luminous electrode covering membrane, 114.1
15... Al wiring connecting the aluminum ζ electrode covering the capacitor oxidized Ht and the tritander electrode, 116.11
7... Aluminum electrode for trimming, 11B...
... Aluminum wiring that crosses the eaves-like oxide film strip, 221
...P@diffused resistance, 222,223...
・Al electric wiring coming out from both ends of the resistor %224,225°2
26.227・・・・・・Alu electric wiring for Torinonda, 2
28.229, 230, 231... Aluminum electrodes for trimming 1232, 233, 234... Aluminum wiring that crosses the eave-shaped oxide film strip. 10/No.l Figure

Claims (1)

[Claims] A semiconductor substrate of one conductivity type, a conductor formed on the semiconductor substrate, and a plurality of wiring electrodes connected to the passive elements formed on the semiconductor substrate through windows formed in the insulating film. and an eaves-like insulating strip provided on the insulating film, the upper part of which extends out into an eave-like shape, and any one of the plurality of wiring electrodes extending over the eaves-like insulating strip. and a conductive strip provided on the insulating film so as to connect between the wiring electrodes, the conductive strip having a break at the insulating strip.