JPS63100171A - Nitride thin film resistor manufacturing equipment - Google Patents

Abstract

PURPOSE:To produce a desired thin nitride film resistor with high accuracy by providing a substrate and target of a transition metal so as to face each other in a reaction chamber and supplying gaseous N2 and inert gas at the flow rates controlled by mass flow controllers into the reaction chamber. CONSTITUTION:The substrate 4 and the target 7 of the transition metal such as Zr are provided to face each other in the reaction chamber 1 where a prescribed vacuum degree is maintained by an oil diffusion pump 10 and an oil rotary pump 21. The thin nitride film of ZrN, etc., is formed on the surface of the substrate 4 by reactive sputtering. The flow rate from a gaseous N2 cylinder 10 and the flow rate from a gaseous Ar cylinder 11 are precisely controlled respectively by the mass flow controllers 14, 15 of the above-mentioned apparatus for producing the thin nitride film resistor and the two gases are supplied to the reaction chamber at such flow rates. These gases are mixed and are then admitted from a gas inflow port into the reaction chamber 1. The thin film resistor having desired characteristics are thereby obtd. with high accuracy.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention precisely controls the flow rate of N2 gas and inert gas into the reaction chamber when producing a thin film of nitride such as ZrN by reactive sputtering. The present invention relates to an apparatus for manufacturing a nitride thin film resistor, which makes it possible to obtain a thin film resistor with desired characteristics.

``Prior art'' The sputtering method for obtaining a thin film resistor of nitride, such as ZrN, generally uses N2 gas and an inert gas (Ar, X
A gas mixture at a constant pressure (e.g.,
This is a method in which the atoms that are knocked out are deposited on a substrate.

However, the amount of the mixed gas introduced into the reaction chamber is an important parameter that influences the characteristics of the thin film, such as its resistivity, temperature coefficient of resistance (TCR), and film formation rate. Conventionally, in order to evaluate the amount of this gas, the characteristics of the thin film produced were controlled by measuring the gas pressure with a vacuum gauge installed in the reaction chamber. Specifically, as shown in FIG. 6(a), an inlet (30) for introducing a constant flow rate of gas is connected to one end of the reaction chamber (1),
An orifice controller (32) is provided at the exhaust port (31) connected to the other end, and the reaction chamber (1) is controlled by a vacuum gauge (33).
The vacuum was controlled to be constant while measuring the internal pressure inside.

In addition, as shown in FIG. 6(b), a gas inlet (30)
A mass flow controller (34) is installed in the vacuum gauge (3).
3) has also been used to control the vacuum to a constant degree.

``Problems to be solved by the invention'' However, conventional vacuum gauges have been unable to precisely control the degree of vacuum required for sputtering.

That is, for sputtering, the reaction chamber was heated to 1O-3To.
It is necessary to achieve a vacuum level of about rr, but it is 1 to 1 O-3 Torr for Paratron vacuum gauges, 10-10-" Torr for Pirani vacuum gauges, and 10""ζ for electromagnetic vacuum gauges.
10-”T.

rr and 10'' Torr required for sputtering were located exactly at the switching point of the vacuum gauge, making it impossible to accurately measure them. Therefore, there was a problem in that it was impossible to precisely control the characteristics of the thin film.

"Means for Solving Problems" The present invention has been made in order to solve the above-mentioned problems. That is, the relationship between the partial pressure of N gas and the flow rate of N2 gas is 2x10'' per Ice/win as shown in Figure 5, for example in the case of the apparatus shown in Figure 1.
' Torr, but there was no vacuum gauge that could accurately measure down to 10-s Torr in the vicinity of 10-" Torr. However, mass flow controllers
ice/min at full scale number 1000cc/win
There are devices that can set the flow rate with an accuracy of .

Therefore, it can be seen that thin film characteristics can be easily controlled using this mass flow controller. Therefore, in the present invention, a substrate for forming a ZrN thin film and a Zr target as a transition metal target are provided facing each other in a reaction chamber, and the pumping capacity of a pump connected to the reaction chamber is maintained at a predetermined value. In an apparatus for manufacturing a thin film resistor by flowing a mixed gas of N gas and an inert gas, the reaction chamber is provided with a gas inlet for flowing the mixed gas, and the gas flow is A mass flow controller that sets the flow rate from the N2 gas cylinder and a mass flow controller that sets the flow rate from the inert gas cylinder are combined at the inlet, and the characteristics of the thin film are controlled by precise control of the gas flow rate by these mass flow controllers. It is something.

"Example" Embodiments of the present invention will be described below based on the drawings.

In Figure 1, (1) is a reaction chamber;
A heater (2) capable of heating up to 350° C. is installed inside the heater (2).
A cylindrical rotating body (3) that rotates slowly at - is provided, and a substrate (4) made of a glass plate for forming a thin film is attached to the outer wall of this rotating body (3).
A rotary shutter (6) with a window (5) opened is provided on the outer periphery of the rotary shutter. Further, a target (7) of, for example, Zr is provided as a transition metal target facing the substrate (4), and this target (7) has a frequency of 13.56 MHz.
(7) A high frequency power source (8) is coupled to apply a power of 1.35 KV. (9) is a magnet.

At one end of the reaction chamber (1), a N2 gas cylinder (10) is installed.
and an inert gas, for example, an Ar gas cylinder (11), are connected via valves (12), (13), and mass flow controllers (14, 15), respectively, and at the other end of this reaction chamber (1), It is connected to the cold trap (17) via the main valve (16), and further includes an orifice (18), an oil diffusion pump (19), and an auxiliary valve (20).
It is connected to an oil rotary pump (21) via. Furthermore, an exhaust pipe (2) is connected between the reaction chamber (1) and the oil rotary pump (21).
2) and are connected via a roughing valve (23).

The reaction chamber (1) is equipped with a baratron vacuum gauge (24) (1-10'') T to measure the internal vacuum degree (pressure).
orr), Pirani vacuum gauge (25) (10 to 10
Measurement of Torr), ionization vacuum gauge (26) (10-
'-10-' Torr) is provided.

Further, a control circuit (27) is provided, which controls not only the mass flow controllers (14) and (15) but also the heater (27).
), main valve (16), orifice (18), roughing valve (23), auxiliary valve (20), high frequency power supply (
8) Furthermore, it is coupled to control the drive unit (28) of the rotating body (3) and the drive unit (29) of the rotary shutter (6). This control circuit (27) further includes the vacuum gauge (2).
4) (25) and (26) are combined, and their data is input in order to prevent the degree of vacuum in the reaction chamber (1) from deviating significantly.

An apparatus for producing a ZrN thin film using the apparatus as described above will be explained.

First, in order to avoid the influence of residual gas, the substrate (4) was heated to 350°C with the heater (2), and the 4.0X10"
-' Evacuate the inside of the reaction chamber (1) to below Torr. Next, in order to clean the surface of the target (7) and the inner wall of the reaction chamber (1), the rotary shutter (6) is closed (window (5)
on the opposite side of the target (7)), flow only Ar gas at 200 cc/win and perform bliss sputtering for 30 minutes.Next, set the Ar gas and N2 gas to the set flow rate values to cause glow discharge. Rotating shutter for 20 minutes (
6) to generate a thin film. After forming the thin film, open the substrate (4).
), the substrate temperature is naturally cooled to 200° C. and purged with Ar gas.

The thickness, specific resistance, and TCR of the formed thin film are measured, and the crystal structure of some samples is analyzed by X-ray diffraction.
Specifically, the film thickness was measured using a stylus-type film thickness meter, and the specific resistance was determined as the product of the film thickness and the sheet resistance measured by the four-needle method.
The TCR was determined by bonding a sample cut out from the substrate (4) and measuring the resistance value using the four-probe method when heated on a hot plate at room temperature and 110°C. (Wavelength: 1.5405 people) using a diffractometer.

Next, the characteristics of the produced ZrN thin film are shown in Figures 2 and 3.
This will be explained based on FIG.

(1) Temperature coefficient of resistance (TCR) Figure 2 shows the mixed gas flow rate, especially the TC for the N2 gas flow lid.
It shows the change in H. Here, the solid line characteristic (A) indicates that the mixed gas flow rate is 200cc/win, the chain line characteristic (B) indicates 100cc/+in, and the dotted line characteristic (C) indicates 70cc/wi.
It shows n. The horizontal axis shows the absolute value of the gas flow rate. For example, if N is 10cc/win, when the total amount is 200cc/win, N2 is 10cc/win.
Ar means 190cc/win in min, total amount 10
N at 0cc/win, A at 10cc/+ain
r means 90cc/win, total amount 70cc/+mi
When n, N3 is 10cc/sin and Ar is 60cc/sin.
It means wzin. The following can be seen from the characteristic diagram in FIG. As the N flow rate increases, the TCR rapidly decreases from about 2000 ppm/deg, and drops to the negative side when the N flow rate is around 5 cc/win.When the N flow rate is further increased, the TCR rises and the N2 flow rate reaches 8 ccllin. There is a peak in the vicinity, but after that it gradually decreases again.The change in TCR up to the peak does not change depending on the total gas flow rate, but after the peak, the smaller the total gas flow rate, the more rapid the change in TCR. is greater than or equal to 0, the TCR change curve has the characteristics (A) (B) (C)
Both intersect with TCR=0 at three points.

(2) Specific resistance N□ Changes in specific resistance with respect to flow rate are shown in FIG. In this characteristic diagram, the total gas flow rate and the horizontal axis of the solid line characteristic (A), the chain line characteristic (B), and the dotted line characteristic (C) are the same as in FIG. 2. The following can be seen from the characteristic diagram in FIG.

When sputtering is performed using only Ar gas, the specific resistance is approximately equal to the bulk value of Zr (41 μΩ) for each gas flow rate. As the N2 flow rate increases, the resistivity becomes approximately the same curve for all three characteristics (A), CB), and (C) up to about 104 μΩ, but once it exceeds 104 μΩ, the changes become more gradual as the total gas flow rate increases. .

(3) Film formation speed FIG. 4 shows the change in deposition rate with respect to N and flow rate.

In this characteristic diagram, the solid line characteristic (A) and the chain line characteristic (B)
, the total gas flow rate and the horizontal axis of the dotted line characteristic (C) are the same as in FIG.

The following can be seen from the characteristic diagram in FIG.

Regardless of the total gas flow rate, the film formation rate decreases rapidly when N8 is introduced, but when the N flow rate exceeds about 10 cc/+min, the decrease becomes gradual and asymptotically approaches around 15 nm/win. It shows the situation. Such a change in film formation rate is generally observed in reactive sputtering, and is thought to be a phenomenon caused by the formation of a compound with a low sputtering rate on the target surface by the target material and the reactive gas. In addition, when sputtering is performed using only Ar gas, the film formation rate is constant at approximately 130 nm/win regardless of the gas flow rate, and no influence of the gas flow rate is recognized.
When two gases are mixed to form reactive sputtering, the film formation rate tends to increase as the total gas flow rate increases.

The following is understood from the characteristic diagrams of FIGS. 2, 3, and 4.

(1) When sputtering is performed using a mixed gas of Ar and N2, the larger the total gas flow rate, the faster the film formation rate.

(2) The specific resistance increases from 40 μΩ1 to 104 μΩ1 by increasing the N2 gas flow rate, and within this range there is little effect on changes in the total gas flow rate.

(3) TCR changes more slowly as the total gas flow rate increases.

In the above embodiment, the case where Zr was used as a transition metal target was explained, but nitride film formation can be similarly performed when using a transition metal target other than Zr such as T i or Ta.

"Effects of the Invention" As described above, the present invention connects N8 gas and inert gas cylinders to the reaction chamber through mass flow controllers, and precisely controls the flow rates by these mass flow controllers to form a thin nitride film. Since the characteristics of the nitride are controlled, a nitride thin film characteristic body having the desired characteristics can be obtained with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the apparatus for manufacturing a nitride thin film characteristic body according to the present invention, and FIG.
3 is a characteristic diagram of the specific resistance of the thin film according to the present invention, FIG. 4 is a characteristic diagram of the deposition rate of the thin film according to the present invention, FIG. 5 is a characteristic diagram of N2 flow rate vs. N2 partial pressure, FIG. 6 is a schematic diagram of a conventional device. (1)...Reaction chamber, (2)...Heater, (3)...
・Rotating body, (4)...Substrate, (5)...Window, (6)
...Rotating shutter, target (Zr) for (7), (
8)...High frequency power supply, (9)...Magnet, (1
0)...N gas cylinder, (11)...Ar gas cylinder, (12) (13)...valve, (14) (
15)...Mass flow controller, (16)...
Main valve, (17)...Cold trap, (1
8)... Orifice, (19)... Oil diffusion pump,
(20)... Auxiliary valve, (21)... Oil rotary pump, (22)... Exhaust pipe, (23)... Roughing valve, (24)... Baratron vacuum gauge, (25 )...
Pirani vacuum gauge, (26)...Ionization vacuum gauge. (27)...Control circuit, (28)...Rotating body drive unit, (29)...Shutter drive unit, (30) River inlet,
(31)...Exhaust port, (32)...Orifice controller, (33)...Vacuum gauge, (34)°゛°°mass flow controller Applicant Fujitsu General Ltd. AS 3 Figure N = 5Lt (cc /min) Fig. 4 N=, 11 quantity (cc/min) Fig. 5 N2 variable (cc/m1n)! 6 Figure

Claims (1)

[Claims] (1) A substrate for producing a nitride thin film and a transition metal target are provided in a reaction chamber facing each other, and while maintaining the exhaust capacity of a pump connected to the reaction chamber at a predetermined value, N_2
In an apparatus that manufactures a thin film resistor by flowing a mixed gas of a gas and an inert gas, the reaction chamber is provided with a gas inlet through which the mixed gas flows, and an N_2 gas cylinder is connected to the gas inlet. A mass flow controller that sets the flow rate from an inert gas cylinder and a mass flow controller that sets the flow rate from an inert gas cylinder are combined, and by precise control of the gas flow rate by these mass flow controllers, a thin film resistor with the desired characteristics can be obtained. An apparatus for manufacturing a nitride thin film resistor, characterized in that: