JPH07106197A - Method of manufacturing capacitor for thin film circuit - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the film deposition rate, to reduce the film deposition on the side wall of the reaction chamber, and to control the film stress which increases when the film deposition rate is increased. A reaction chamber 20 having a reaction gas introduction pipe 24 and a vacuum exhaust port 21, a substrate table 28 on which a substrate 29 is placed in the reaction chamber 20, and a heater block 24 for heating the substrate table 28.
In the plasma CVD apparatus including the high frequency electrode 22 provided at a position facing the substrate table 28, the distance between the electrode 22 and the substrate table 28 is set to 4 to 10 mm, and low frequency power is supplied to the substrate table 22. , Plasma electrode 22
By confining it between the substrate and the substrate table 28 to increase the plasma density,
The film deposition rate on the substrate 29 is increased, and
By supplying low frequency power to the film, ion bombardment of the film is caused to increase the film density and control the film stress. With this configuration, it is possible to improve the production efficiency of the thin film circuit capacitor and form a highly reliable insulating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a capacitor for thin film circuits in the field of consumer equipment, which is required to be small and lightweight, and industrial equipment, which is required to have high precision and high quality.

[0002]

2. Description of the Related Art In recent years, thin film circuits applying thin film technology have
It is used in consumer equipment that requires small size and light weight, and industrial equipment that requires high precision and high quality. FIG. 3 shows a cross-sectional view of the thin film circuit board. Reference numeral 1 is a substrate, 2 is a resistor for a resistor, 3 is an electrode, 4 is a conductor wiring, 5 is a capacitor insulating film, and 6 is a capacitor electrode. Substrate 1 as material
Is alumina, resistor 2 is nichrome, electrode 3, conductor wiring 4,
Each of the capacitor electrodes 6 is made of gold or copper, and chromium is used as the base adhesion layer. Nichrome,
Gold, copper, chromium, etc. are formed by the sputtering method. As a method for forming the capacitor insulating film 5, there are a CVD method, a sputtering method, a vapor deposition method, and the like, but as the high-purity film, the CVD method can obtain the highest-purity film. Among the CVD methods, a plasma CVD method that can be formed at 400 degrees or less is generally used.

A plasma CVD method for forming an insulating film of a thin film circuit capacitor will be described below with reference to the drawings, in which a SiN film is deposited.

In FIG. 4, the reaction chamber 7 has a vacuum exhaust port 8 and is grounded. Reference numeral 9 denotes an electrode, which is a matching tuner for receiving power from the high frequency oscillator, and a high frequency power supply unit 10.
Supplied through. The electrode 9 has a gas outflow hole 12 for dispersing and supplying the reaction gas supplied from the reaction gas introduction pipe 11 into the reaction chamber 7. Reference numeral 13 is an insulating ring for insulating the reaction chamber 7 and the electrode 9. Reference numeral 14 is an insulating pipe for insulating the reaction gas introducing pipe 11 and the electrode 9 from each other. Reference numeral 15 denotes a substrate table on which the substrate 16 is placed, which is grounded. The distance between the electrode 9 and the substrate stand 15 is 20 m
It is set to about m. Reference numeral 17 is the substrate table 15 and the substrate 1.
It is a heater block for heating 6, and a heater and a thermoelectric body (not shown) are embedded therein. Reference numeral 18 is an insulating ring for reducing heat transfer between the heater block 17 and the reaction chamber 7. Electrode 9, insulating ring 1
3, O-ring seals (not shown) are used for the heater block 17 and the insulating ring 18 to maintain the vacuum in the reaction chamber 7. Reference numeral 19 is a water cooling groove for flowing cooling water so that the O-ring is not heated to more than 200 degrees.

A CVD apparatus and an S having the above-mentioned structure
The process of forming the iN film will be described. The substrate 16 on the substrate table 15 is heated to about 300 degrees by the heater block 17,
In the reaction chamber 7, 200 sccm of SiH ₄ (monosilane) gas and 1000 sccc of N ₂ (nitrogen) gas were introduced from the gas outlet 12.
The reaction chamber 7 is vacuum-held at about 2 Torr with a flow of m, NH ₃ (ammonia) gas of 600 sccm. 1 for electrode 9
400W of high frequency power of 3.56MHz was applied to the electrode 9
A plasma discharge is generated between the substrate base 15 and the substrate base 15. SiH ₄ gas, N ₂ gas, and NH ₃ gas as the reaction gas in the reaction chamber 7 are decomposed by the energy of plasma, and S on the substrate 10
Deposit an iN (silicon nitride) film.

[0006]

However, in the above-mentioned method, the film deposition rate is as slow as about 2000 angstrom / min, and the gas excited / dissociated by the discharge causes the gas in the electrode 9, the heater block 17 or the reaction chamber 7 to flow. When the film reaches the sidewall and film deposition occurs, CF _{4 is} deposited each time the film is deposited.
Since it is necessary to introduce and remove an etching gas such as (carbon tetrafluoride) gas, there is a problem that productivity is poor.

In view of the above-mentioned conventional problems, the present invention can reduce the film deposition on the side wall of the reaction chamber, increase the film deposition rate, and control the film stress generated by increasing the film deposition. The purpose of the present invention is to manufacture a thin film circuit capacitor by the plasma CVD method.

[0008]

The method of manufacturing a capacitor for a thin film circuit according to the present invention comprises:
A reaction chamber having a reaction gas inlet and a vacuum exhaust port, a substrate table on which a substrate is placed, a heater block for heating the substrate table, and a position opposed to the substrate table, and high-frequency power is supplied. CV consisting of high frequency electrode
In the D device, the distance between the substrate stand and the high-frequency electrode is 4 to 10
It is characterized in that the insulating film is formed by setting the pressure in the reaction chamber to 1 to 10 Torr. Further, a low-frequency power of 200 to 800 KHz is applied to the substrate table in order to form a more reliable insulating film.

[0009]

According to the method of the present invention, the distance between the electrode and the substrate table is set to be narrower than 4 to 10 mm as compared with the usual 20 mm, so that the plasma is confined between the electrode and the substrate table to increase the plasma density. Therefore, the number of molecules of the reaction gas excited and dissociated by the energy of electrons generated by the plasma discharge increases, and the film deposition on the substrate increases. Further, by confining the plasma, film deposition on the side wall of the reaction chamber is reduced, and the number of etchings in the reaction chamber can be reduced. In this way, the film deposition rate can be increased and the number of etchings can be reduced, resulting in a dramatic improvement in productivity.

On the other hand, when the film deposition increases, the film density of the deposited film decreases and the film stress (tensile stress) increases.
As the dimensions of thin film circuit capacitors, in the case of SiN film,
The dielectric constant is about 9, and if the film thickness is 4000 Å, 10 ³ PF (picofarad) is 3 m.
m, to obtain a larger capacity capacitor,
Larger dimensions are required and film stress must be controlled for reliability. By supplying low-frequency power to the substrate, ions that could not follow at high frequencies can also follow, causing ion bombardment to the film, and while the film is deposited while receiving this ion bombardment, the film density increases and the film density increases. Stress changes from tensile stress to compressive stress.
Thus, the film deposition rate can be increased and the number of etchings can be reduced to improve the productivity, and the film density can be increased to control the film stress that causes cracks.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma CVD method for forming an insulating film of a thin film circuit capacitor according to an embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the reaction chamber 20 has a vacuum exhaust port 2
1 and is grounded to earth. 22 is an electrode for plasma discharge. High frequency oscillator (frequency 13.56MH
Power from z) is supplied to this electrode 22 through a matching tuner, a filter and a high frequency power supply 23. The electrode 22 has a gas outflow hole 25 for supplying the reaction gas, which is supplied from the reaction gas introducing pipe 24, into the reaction chamber 20 in a shower shape. Reference numeral 26 is an insulating ring made of alumina for insulating the reaction chamber 20 and the electrode 22. Reference numeral 27 is an insulating tube made of alumina for insulating the reaction gas introducing tube 24 and the electrode 22. Reference numeral 28 denotes a substrate table on which a substrate 29 is placed. 30 is a substrate stand 28
And a heater block for heating the substrate 29, in which a heater and a thermocouple (not shown) are embedded. Reference numeral 31 is an insulating ring made of an insulating material (for example, alumina) for reducing heat transfer between the heater block 30 and the reaction chamber 20. Electric power from a low frequency oscillator (400 KHz) is supplied to the substrate table 28 through a matching tuner / filter and the low frequency power supply unit 32. 33
Is an insulating ring made of alumina, and the reaction chamber 20 is kept in vacuum by using an O-ring. Electrode 22, insulating ring 2
6. An O-ring seal (not shown) is also used for the heater block 31 to maintain the vacuum inside the reaction chamber 20. Three
Reference numeral 4 is a water cooling groove for flowing cooling water so that the O-ring is not heated to more than 200 degrees. Numeral 35 indicates about 1 to about 1 from the electrode 22 so as to prevent discharge between the electrode 32 and the side wall of the reaction chamber 20.
It is an upper side shield plate provided so as to maintain a gap of 2 mm and is grounded. 36 is the substrate table 28 and the reaction chamber 2
0 to about 1 to prevent the occurrence of discharge with the side wall.
It is a lower side shield plate provided so as to maintain a gap of 2 mm and is grounded.

The case of depositing a SiN film with the plasma CVD apparatus configured as described above will be described.

The substrate 29 is heated to about 3 by the heater block 30.
The reaction chamber 20 is heated to 00 ° C., and gas is discharged from the gas outlet holes 25 into the reaction chamber 20.
200 sccm of H ₄ (monosilane) gas, 1000 sccm of N ₂ (nitrogen) gas, and 600 scc of NH ₃ (ammonia) gas
In the state of m flow, a vacuum is maintained in the reaction chamber 20 at about 2 Torr. A high-frequency power of 13.56 MHz is applied to the electrode 22 through the high-frequency power supply unit 400 at 400 W to cause plasma discharge between the electrode 22 and the substrate table 28. Further, 200 W of low frequency power of 400 KHz is applied to the substrate table 28. SiH ₄ gas, N ₂ gas, NH as a reaction gas in the reaction chamber 20
_{The 3} gas is excited and dissociated by the electrons in the plasma, and deposits a SiN (siliman nitride) film on the substrate 29. During this film formation, the distance between the electrode 22 and the substrate 29 should be 3 to 1
As a result of continuously changing the film thickness to 5 mm and depositing films at each distance, the plasma became plasma not only between the electrode 22 and the substrate 29 but also so as to wrap them around 11 mm or more. Further, when the distance is 10 mm or less, the electrode 22
The discharge occurred as if the plasma was trapped between the substrate 29 and the substrate 29, and did not occur at 3 mm or less. Further, FIG. 2 shows the film deposition rate with respect to the distance between the electrode 22 and the substrate 29 when the low frequency power is OW. If the pressure is 1 Torr or more when the distance is 11 mm or more, the abnormal discharge region occurs.
I went with rr. When it was 10 mm or less, the pressure was 2 Torr. 1
When the thickness is 0 mm or less, the deposition rate is 8000 angstroms / minute, whereas when the thickness is 11 mm or more, the film deposition rate is approximately 4,000 angstroms / minute or less. At this time, when the stress of the deposited film is measured while changing the distance, it becomes a tensile stress, which is about 1.5 × 10 9 dynes / cm ^{2 when} the distance between the electrode 22 and the substrate 29 is 11 mm or more, whereas it is 10 mm.
Below, it doubled to 3 × 10 ⁹ dynes / cm ² . On the other hand, even when the thickness is 10 mm or less, when the low frequency power of 400 KHz is changed to 0 to 300 W and the films are deposited on the substrate pedestal 28, respectively, the low frequency power of 0 to 150 W is tensile stress, but exceeds 150 W. That turned into compressive stress. This is because at low frequencies, both ions and electrons in the plasma can follow the electric field, so that ions are bombarded into the substrate 28 to form a dense film. By applying the low frequency power in this way, the stress can be controlled. That is, even if the distance between the electrode 22 and the substrate 29 is narrowed to 10 mm or less and the film deposition rate is increased, a low stress film can be obtained by applying low frequency power. Further, when the stress was measured by changing the frequency of the low frequency power from 50 to 1000 KHz, a remarkable effect was observed at 800 KHz or less.

As described above, according to this embodiment, the electrode 22
By setting the distance between the substrate table 28 and the substrate table 28 to be 4 to 10 mm, plasma is confined between the electrode 22 and the substrate table 28 and the film deposition rate is increased.

Further, the distance between the electrode 22 and the substrate 29 is 11
When the thickness is 10 mm or less, the film deposition amount on the side wall of the reaction chamber 20 is smaller than when the thickness is 10 mm or more. Therefore, the number of times the film deposits in the reaction chamber 20 are removed can be reduced, and the productivity can be improved.

Further, a low frequency power (400
By applying (KHz), it is possible to deposit a good-quality SiN film with small stress even if the film deposition rate increases.

In the above embodiment, the case of depositing the SiN film has been described, but another insulating film, for example, S
It can also be applied to the formation of an iO ₂ film or the like.

In the above embodiment, the high frequency power is 1
Although it is set to 3.56 MHz, it is not particularly limited to this frequency as long as it is a high frequency.

In the above embodiment, the low frequency power is 4
Although it was set to 00 KHz, the effect of reducing the film stress is large in the range of 200 KHz to 800 KHz.

[0021]

According to the present invention, as described above, the distance between the electrode and the substrate table is set narrower than 4 to 10 mm as compared with the usual 20 mm, so that the plasma is confined between the electrode and the substrate table. The increased density increases the film deposition rate on the substrate, and the plasma is trapped,
Since the film deposition on the side wall of the reaction chamber is reduced, the removal work can be reduced and the productivity is improved. Generally, when the film deposition rate increases, the film density decreases and the film stress (tensile stress) increases. However, in the present invention, by supplying low frequency power to the substrate, ions that could not follow at high frequency can follow up. Ion bombardment occurs, and the film density increases due to the film deposition while receiving the ion bombardment, and the stress of the film changes from tensile stress to compressive stress. Therefore, the film deposition rate can be increased, the deposition on the side wall of the reaction chamber can be reduced, and the removal work can be reduced to improve the productivity, and the film density can be increased to control the film stress that causes cracks. It is possible to obtain a high-quality film that is free from cracks.

[Brief description of drawings]

FIG. 1 is a sectional view of a plasma CVD apparatus for forming an insulating film of a thin film circuit capacitor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a film deposition rate and a distance between an electrode and a substrate table.

FIG. 3 is a sectional view of a thin film circuit board.

FIG. 4 is a sectional view of a conventional plasma CVD apparatus.

[Explanation of symbols]

 20 Reaction Chamber 22 Electrode 23 High Frequency Power Supply Section 24 Reactive Gas Introducing Tube 28 Substrate Stand 29 Substrate 30 Heater Block 32 Low Frequency Power Supply Section

Claims (2)

[Claims] 1. A reaction chamber having a reaction gas introducing port and a vacuum exhaust port, a substrate stage on which a substrate is placed in the reaction chamber, and the substrate stage being heated as means for forming an insulating film of a thin film circuit capacitor. In a plasma CVD apparatus including a heater block and a high-frequency electrode that is arranged at a position facing the substrate table and is supplied with high-frequency power, the distance between the substrate table and the high-frequency electrode is set to 4 to 10 mm, A method of manufacturing a thin-film circuit capacitor, which comprises forming an insulating film at a pressure of 1 to 10 Torr. 2. The method for manufacturing a thin film circuit capacitor according to claim 1, wherein low frequency power of 200 to 800 KHz is applied to the substrate table.