JPH0444260A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the contact resistance of an Al electrode, further an Al electrode of a first layer and an Al wiring electrode of a second layer with a CrSiX thin film resistor by first the resistor on an insulating film, and then forming the Al wiring electrode of the second layer thereon. CONSTITUTION:An Si substrate 1 has an oxide insulating film 2, an electrode forming opening window 2 is opened at the film 2, sputtered to cover it with a thin film, selectively reactive ion etched to expose an opening window 3, and a thin film resistor 4 is formed (a). Then, after an SiO2 thin film generated by spontaneous oxidation in the bottom of the window 3 is removed, it is covered with an Al film by sputtering, selectively wet etched to form an Al electrode 5 of a first layer (b). It is coated with photosensitive polyimide 6, exposed, developed, thermally cured, then selectively etched to expose an Al electrode 5 and two electrode regions 7 to be formed on the resistor (c). Then, after thin layers of spontaneously oxidized Cr2O3 on the surfaces of the electrode 5 and the resistor 4 are removed by RF etching, it is covered with an Al film under the same conditions as those in the paragraph (b), patterned, and wiring electrodes 8, 8' a second layer are formed.

Description

Detailed Description of the Invention [Summary] A method for manufacturing a semiconductor device having a thin film resistor of CrS+,D (X represents a number in the range of 1 to 2).
Aiming at improving the contact resistance between the thin film resistor and the l'i electrode, the method of the first invention forms the first layer of AA main electrode in the opening window of the insulating film and uses photosensitive polyide. CrSi, 0
Region where the electrode of the thin film resistor is to be formed and Aβ of the first layer
The electrode is exposed and RF etching is performed to a depth of 60 to 120 people in terms of 5in2 to remove Cr2O3 on the surface of the resistor produced by natural oxidation and Al on the surface of the first layer Aj' electrode.
The method of the second invention is configured to form a second layer wiring electrode after removing a thin layer of CrS+ and CrS+.
, D with a thickness of 100 mm in the area where the electrodes of the thin film resistor are to be formed.
~5000 people formed the first layer of AI main electrodes, performed RF etching to remove the naturally oxidized AI,03 thin layer on the electrode surfaces, and then sputtered and patterned a CrS+,0 thin film. to form a thin film resistor, and further perform RF etching to a depth of 60 to 120 mm in terms of 5iO7 to remove the first layer of Aβ electrodes and Cr.
A produced by natural oxidation on the surface of Si, O thin film resistor
After removing the thin layer of 12O2 and Cr2O3, a second layer of wiring electrodes is formed.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device having a CrSi,O thin film resistor. In recent years, thin film resistors have a sheet resistance of 1Ω/4 or more and a temperature coefficient of resistance of ±1oop.
pm/ is required to be as small as possible. For this, (:r3iX or CrS,0 (X represents a number in the range 1 to 2) is used.

[Conventional technology]

Note: In the method of manufacturing a semiconductor device having a CrSi thin film resistor, a problem has been that the contact resistance between the CrSi, O thin film and the ^β electrode is large. This is a needle, 03 or A I by natural oxidation on the surface of CrSi, 0 or i.
This produces thin layers of t z03 and these have insulating properties. In addition, the ^l electrode of the first layer and (:rS+,
0 After forming the thin film resistor, a flattened interlayer insulating film is formed, and a wiring electrode is formed by opening an opening window for forming the second layer electrode. Al2O2 and Cr2 on the surface of CrS+,0 thin film resistor
A thin layer of O3 is formed.

This can be removed by RF etching, but if RF etching is performed with the opening window for forming the first AI electrode open, it also has the disadvantage of damaging the bulk Si. In addition, chemical vapor deposition (C
The production process by VD) includes coating of 1-PSG, B-PS
It was a complicated process, requiring G coating, liquid OCD planarization, and controlled reactive ion etching.

[Problem to be solved by the invention]

The present invention is applicable to manufacturing a semiconductor device having a CrS+,Q thin film resistor and an AI! It
Furthermore, the main objective is to improve the contact resistance between the first layer Aβ electrode and the second layer Al wiring electrode.

Means for Solving Problem C] The above problem is a method for manufacturing a semiconductor device having a CrSi, 0 thin film resistor, which includes: (a) forming an 81 substrate t in which an opening window for forming an electrode is formed in an insulating film; , O (X represents a number in the range of 1 to 2) thin film was sputtered and patterned to form Cr51. D thin film resistor is formed, (b) 0.
After pretreatment with 5-5.0% HF, the first layer ^1 is sputtered and patterned to form the first layer ^1 on the opening window.
forming electrodes, (c) applying photosensitive polyimide, exposing, developing, and curing with heat to form a flattened interlayer insulating film;
Next, by selective etching, the electrode formation region of the CrSi,0 thin film resistor and the ^β electrode of the first layer were exposed, and (d) the Cr2O on the surface of the CrSi,0 thin film resistor, which was generated by natural oxidation, and A I 2 on the surface of the first layer ^l electrode.
After removing the thin layer of 03 by RF etching to a depth of 60 to 120 people in terms of 8102, (e) the second layer ^! CrSi is sputtered and patterned.
, a method characterized by including a step of forming a wiring electrode on the electrode formation region of the thin film resistor and the ^β electrode of the first layer, and (a) opening an opening window for electrode formation in the insulating film. The first layer of AI is sputtered and patterned on the Si substrate prepared to form an opening window for forming an electrode, and a CrS+,0 (X represents a number in the range of 1 to 2) thin film resistor to be formed. A first layer of 100 to 5,000 electrodes with a thickness of 100 to 5,000 people is formed in each of the two electrode formation regions, and (b) a thin layer of A A 203 that is naturally oxidized and generated on the surface of the first layer ^l electrode is RF etched. (c) sputtering CrS+,0,
Cr5i is patterned to straddle the two electrode formation regions.
xO thin film resistor is formed, (d) further 5102 conversion 6
Perform RF etching to a depth of 0 to 120 people and create the first layer of AI! A It 2i3 generated by natural oxidation on the surfaces of It and CrSi thin film resistor, respectively.
and Cr, 0. This problem can be solved by a method characterized by including the steps of (e) sputtering and patterning a second layer of AI to form a wiring electrode after removing a thin layer of the same.

[For production]

In the method of the first invention, a CrS+XO thin film resistor is first formed on an insulating film, and a second layer of wiring electrodes is formed on this. The method of the second invention first forms two first layer l electrodes in two electrode formation regions of a Cr 31x O thin film resistor to be formed on an insulating film, and then CrSi, which straddles these, In addition to forming the 0 thin film resistor, a second layer ^l wiring electrode is formed in this electrode formation region.

The method of the first invention requires removal of the native oxide by RF etching once, whereas the method of the second invention requires removal twice.

However, in the second invention, since the CrS+,0 thin film resistor is sandwiched between the Al electrodes of the first layer and the second layer, it has the advantage of high mechanical strength.

Note that in both methods of the invention, the first Al electrode is formed in the opening window for electrode formation in the insulating film before RF etching, so that the RF etching for oxide removal is applied to the bulk Si through the opening. It will not reach you and cause any damage.

RF etching of the thin layer of Cr, O, produced by natural oxidation on the surface of the CrSi, O thin film resistor needs to have a depth of 60 to 120 people in terms of S10□.
If it is thinner than 0, the removal of oxide will not be sufficient, and if it is deeper than 120, the thin film resistor, which is about 200, may be damaged.

In the insulating film with the opening window for electrode formation, the bulk Si exposed at the bottom of the window is naturally oxidized and becomes a thin layer of 5102, so it is removed with 0.5 to 5.0% HF. When the concentration of HF is lower than 0.5%, the removal of SiO□ is not sufficient, and when it is higher than 5.0%, it does not dissolve the CrSi but damages the oxide insulating film.

Note that the method of the first invention uses photosensitive polyimide as the interlayer insulating film, so PSG by conventional CVD is not used.
In contrast, the planarization process can be simplified. Of course, this can also be applied to the second invention.

Since the CrSi,0 thin film resistor is extremely thin, usually about 20 OA, the method of the second invention prevents film breakage due to steps when this thin film is deposited on the first layer of Al electrode. Easy to occur. In order to prevent this, the thickness of the first layer L film is 100~5.
000 A, it is necessary to reduce the level difference.

〔Example〕

Example 1 As an embodiment of the method of the first invention, the Si
The substrate 1 has an oxide insulating film 2 with a thickness of 4000 nm, an opening window 3 for forming an electrode is formed in this, and CrSi is deposited at a power of 0.7 kW in Ar at 9 mTorr. A thin film having a thickness of 200 mm was deposited by sputtering D for 20 minutes, and the opening window 3 was etched with Na by selective reactive ion etching to form a thin film resistor 4 (a).

Next, after pretreatment with 1.0% HF for 10 seconds to remove the 5in2 thin layer generated by natural oxidation at the bottom of the aperture window 3, 3. A 9,000-layer thick Al film was deposited by sputtering at the output of QkW, and 5
Selective wet etching was performed using 13P[11, 0° C.] to form the first layer of Al electrode 5 (b).

Photosensitive polyimide 6 was coated by a conventional method, exposed to light, developed, thermally cured, and then selectively etched to form A! The electrode 5 and the two electrode regions 7 to be formed on the resistor were exposed (C).

13.5MHz in 8mTorr Ar, 0.8k
RF etching is performed so that the depth becomes 100A when converted to 5in2 with the output of W, and the thin layer of natural oxidation^1203 and the Cr51. After removing a thin layer of naturally oxidized Cr, 03 on the surface of the ON film resistor 4, the thickness was reduced to 1.51 cm under the same conditions as in (b). A film of Ia was deposited and patterned to form a second layer wiring electrode 8.8' (d
).

C'rSi,0 thin film resistor-A1 electrode contact area 16X
The contact resistance for 6 μ2 was 10 mΩ.

Example 2 As an embodiment of the method of the second invention, 81 shown in FIG.
The substrate has an oxide insulating film 2 with a thickness of 4,000 nm, an opening window 3 for forming an electrode is opened, and pre-treatment with 1.0% HF is performed for 10 seconds. After removing the thin layer, deposit a ^1 thin film to a thickness of 1000 nm by sputtering in Ar at lQmTorr with a power of 3 kW and selectively etching with H, PD, at 50 °C to form a thin film on the bulk Si. First layer Al electrode and Cr to be formed
Si. 0 AI of the first layer under the thin film resistor 4! (a).

13.5MHz, 1.0 in 10mTorrOAr
5. The ^l electrode of the first layer is etched by RF etching with a power of kW.
After removing the thin layer of 03 produced by natural oxidation on the surface of 5', sputtering was performed for 20 minutes at a power of 0.7 kW in Ar at 9 mTorr to form a Cr layer with a thickness of 200 nm.
An S+,0 thin film was formed and a thin film resistor 4 was patterned by selective reactive etching (b).

Furthermore, as in (b), the thickness is 100 in terms of SiO□.
After removing the naturally oxidized Cr2D and thin layer on the surface of the thin film resistor 4 by RF etching, a second layer of Ar with a thickness of 7000 A was deposited in the same manner as in (a), and by selective etching. 1st layer Al electrode, wiring electrode 5'.
8' was formed (C).

CrSi,O thin film resistor-A for the area of the insulating layer occupied by the β electrode of the first layer 4×642! The contact resistance of the electrode was 5 mΩ.

〔Effect of the invention〕

The semiconductor device according to the method of the present invention has the advantage that the contact resistance between the Cr5IXO thin film resistor and the Alt&pole is extremely small. In addition, when removing oxides on the conductor surface by RF etching, the opening window is covered with the first layer of Al electrode, so 8
Since the Ar wiring is formed after forming the thin film resistor, there is no damage to the l wiring due to selective etching of the thin film.

Furthermore, the method of the first invention can form a planarized interlayer insulating film in a simple process, and the method of the second invention can form a planarized interlayer insulating film in a simple process.
The rSi0 thin film resistor has the feature that it is firmly sandwiched between the lii poles of the first layer and the second layer.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an embodiment of the first invention, and FIG. 2 is a process diagram showing an embodiment of the second invention. 1...81 substrate, 2... oxide insulating film, 3...
... Opening window for electrode formation, 4... CrS+, O thin film resistor, 5... L electrode of first layer, 6... Flattening interlayer insulating film, 7... Electrode formation region of resistor , 8・8'... Wiring electrode.

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device having a thin film resistor, which comprises: (a) forming a protective film with openings for electrode formation on a semiconductor substrate; and then depositing a thin film on the protective film. sputtering and patterning to form a thin film resistor; (b) sputtering and patterning a first layer electrode material to form a first layer electrode in the opening window; (c) an interlayer insulating film. Then, selective etching is performed to expose the electrode formation region of the thin film resistor and the first layer electrode, and (d) the oxide film on the surface of the thin film resistor, which is generated by natural oxidation, is removed by RF etching. After the removal, the second layer electrode material is sputtered and patterned to form a wiring electrode on the electrode formation region of the thin film resistor and the first layer electrode. A method for manufacturing a semiconductor device. 2. A method for manufacturing a semiconductor device having a thin film resistor, comprising: (a) forming a protective film with openings for electrode formation on a semiconductor substrate, and then sputtering and patterning a first layer of electrode material; Then, a first layer of electrode is formed in the opening window for electrode formation, (b) the thin film is sputtered and patterned to form a thin film resistor, (c) further RF etching is performed to form the thin film resistor. A method for a semiconductor device, comprising the steps of: (d) sputtering and patterning a second layer electrode material to form a wiring electrode after removing a natural oxide film formed on the surface of the semiconductor device.