JPH0444259A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the contact resistance of a bulk Si-Al electrode by sputtering a CrSiX thin film on an Si substrate in which an electrode forming opening window is opened at an insulating film, annealing it to modify it to a thin layer, patterning it to form a resistor, removing an SiO2 layer generated in the bottom of the window, sputtering Al, patterning it, and forming electrodes on an electrode forming region and in the window. CONSTITUTION:An Si substrate 1 is thermally oxidized by a normal method, an oxide insulating film 2 of 400Angstrom of thickness is formed, and an electrode forming opening window 3 is opened by selective etching (a). An output sputtering is conducted at 0.5kW of output in Ar of 10mTorr for 10 min to form a CrSiX thin film 4 of 200Angstrom of thickness is formed (b). Thereafter, after the surface of the thin film is modified to a CrSiXNO thin film, and a thin film resistor 5 is formed by selectively reactive ion etching (c). In the substrate of this state, a spontaneously oxidized SiO2 thin film present at the bottom of the window 3 is removed. Then, the entire surface is covered with Al 900Angstrom thick by Al sputtering, selectively wet etched, and Al electrodes 6, 6' are formed in the window 3 and in the electrode forming region of the resistor 5 (d).

Description

Detailed Description of the Invention [Summary] CrSix (x represents a number in the range of 1 to 2)
-A! In order to improve the contact resistance of the electrode, the surface of the CrSi thin film was modified to a CrSixN(] thin layer by heating to 400-480°C in a mixed gas of N2 and 02, and the contact resistance was 0.5-5. After processing with .0% HF, a β electrode is formed.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device having a crs1M thin film resistor. In recent years, thin film resistors have a sheet resistance of IKΩ/unit or higher and a temperature coefficient of resistance of ±1100.
pp/ is required to be as small as possible. CrSix or [:rSi, 0 (x represents a number in the range 1 to 2) is used for this.

[Conventional technology]

5102 generated by natural oxidation on the surface of bulk S1
A thin layer is present. When a Si substrate having a Cr51M resistor is subjected to HF treatment for the purpose of removing this, the [r3iX thin film is also dissolved. Therefore, conventionally, a semiconductor device having a Cr5lX resistor has not been subjected to HF treatment. Therefore, the bulk Si −Aj! The disadvantage was that the contact resistance between the electrodes was large.

[Problem to be solved by the invention]

The present invention modifies the surface of a crslK thin film while maintaining its conductivity, and also allows S
The purpose of this study is to find HF treatment conditions that can remove the naturally oxidized SlO□ thin layer at the bottom of the opening window of the i-substrate, thereby improving the contact resistance of the bulk 5i-Aβ electrode.

[Means to solve the problem]

The above problem is a method for manufacturing a semiconductor device having a CrSix thin film resistor, and (a) CrSix (x is a number in the range of 1 to 2) Cr5lX
The surface of the thin film is coated with Cr51. Modified into a thin layer of NO (x represents a number in the range of 1 to 2), patterned the CrSix thin film to form a resistor, and (c) treated with 0.5 to 5.0% HF. Then, at the bottom of the opening window, the surface of the bulk S1 is naturally oxidized and the thin layer of Sin is removed, and (iv) Af is sputtered and buttered to form the electrode forming area of the CrSix thin film resistor and the opening window. This problem can be solved by a method characterized by including a step of forming an electrode.

[For production]

According to the present invention, when the CrSix thin film is annealed, the surface is modified into a CrSixN01 layer. CrS+
, NO has conductivity and is not soluble in 0.5-5.0% HF. The annealing temperature of CrSix is 400
If it is lower than 480°C, the time required for modification will be longer, and if it is higher than 480°C, it will have an adverse effect on the bulk S1. The concentration of HF is
If it is thinner than 0.5%, the natural oxidation 5in2 on bulk Si cannot be removed, and if it is thicker than 5.0%, the modified CrSixNO will also be consumed, thereby damaging the CrSix thin film.

When performing kneeling in a cylindrical furnace that allows air to flow in, nitrogen is applied in the direction of the array for 15 to 30 minutes to a plurality of substrates arranged so that the substrate surfaces are perpendicular to the axial direction of the furnace.
It is convenient to send at a flow rate of 50β/min.

If the flow rate is less than 15A/min, insulating Cr2O
3, and the effect does not change even if the amount is more than 50β/■in.

Furthermore, if the 83PO4 wet etching temperature for patterning Af is lower than 40°C, the etching time will be long, and if it is higher than 60°C, side etching will occur.

This method can be used to manufacture bipolar or MOS type semiconductor devices.

〔Example〕

The Si substrate 1 shown in FIG. 1 was thermally oxidized by a conventional method to form an oxide insulating film 2 having a thickness of 4,000 yen, and an opening window 3 for forming an electrode was opened by selective etching (a).

CrS with a thickness of 200 mm was subjected to 8-cush bumper for 10 minutes at an output of 0.5 KW in lQ mTorrOAr.
+x thin film 4 was formed (b).

Thereafter, the substrate was placed in a cylindrical open furnace (not shown) with an inner diameter of 15 cm so that the substrate surface was perpendicular to the axial direction of the furnace, and heated at 450°C for 30 minutes while introducing N2 from one end of the cylinder at a flow rate of 30 A/+nin. After annealing for a minute to modify the surface of the Cr5IX thin film into a CrSi-NO thin layer, a thin film resistor 5 was formed by selective reactive ion etching (c).

The substrate in this state was pretreated with 1% HF for 10 seconds to remove the naturally oxidized 5iO7 thin layer present at the bottom of the opening window 3.

At this time, the thin film resistor was not affected.

Next, in Ar with lQ mTorr, AI with an output of 3KW
Sputtering is performed to deposit Al with a thickness of 9000 nm on the entire surface, and selective wet etching is performed with H, PO at 50° C. to form an Al electrode 6 in the opening window 3 and the electrode formation area of the thin film resistor 5. .6' was formed (d).

The contact resistance of the bulk 5i-Al electrode with a contact area of 4×6#-” was 10Ω.

〔Effect of the invention〕

According to the method of the present invention, the bulk S1 at the bottom of the opening window can be pretreated with HF before forming the Al electrode, and the bulk S1 can be pretreated with HF before forming the Al electrode.
Contact formation between the i and (rS I M thin films and the Al electrodes can be performed simultaneously. This allows ICs with low temperature coefficients and high resistance thin film resistors, that is, D
/A, greatly contributed to the development of A/D converters.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an embodiment of the method of the present invention. 1...Si substrate, 2...insulating film, 3...
Opening window for electrode formation, 4...Cr518 thin film, 5-=CrSiX thin film resistor, 6...Al electrode.

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device having a CrSi_x thin film resistor, which comprises: (a) forming a protective film with openings for electrode formation on a semiconductor substrate, and then sputtering a CrSi_x thin film; (b) The surface of the CrSi_x thin film is coated with CrSi_xNO
(c) treatment with HF to remove natural oxidation formed on the surface of the semiconductor substrate exposed at the bottom of the opening window; A method for manufacturing a semiconductor device, comprising the steps of: (d) sputtering and patterning an electrode material to form an electrode in an electrode formation region and an opening window of a CrSi_x thin film resistor. 2. The method according to claim 1, wherein the CrSi_xNO modification is carried out in a mixed gas of N_2 and O_2 while heating at 400 to 480°C.