JPH04288818A - Semiconductor manufacturing apparatus and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the uniformity and the reproducibility of the distribution of a formed film by providing a DC detecting/control-signal outputting means which detects and compares the DC voltages of counter electrodes and outputs a phase control signal into a phase control means based on the result, and adjusting the phase difference so that the DC voltages become approximately equal. CONSTITUTION:An introducing port 18 and a discharging port 19 of reaction gas are provided in a pressure reducible chamber 12. A holding tool 14 for mounting a film body to be formed is provided between counter electrodes 13a and 13b in the chamber 12. A phase control means 17 for adjusting the phase relationship between the AC voltages which are supplied and applied from AC power supplies 15a and 15b connected to the counter electrodes 13a and 13b is provided. A DC detecting/ control-signal outputting means 16 for detecting and comparing the DC voltages of the counter electrodes 13a and 13b and outputting the, phase control signal into the phase control means 17 based on the result is provided. Thus, the phase difference is adjusted so that the DC voltages become approximately equal, and the film can respectively continuously be formed.

Description

[Detailed description of the invention]

[0001] (Table of Contents) ・Industrial application field ・Conventional technology (Figure 7) ・Problem that the invention aims to solve ・Means to solve problems ・Effect ·Example (1) First embodiment (Fig. 1, Fig. 5) (2) Second embodiment (Figures 2 to 4, and 6) - Effects of the invention

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device, and more particularly, to a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device in which a film is formed on a film-forming object between opposing electrodes. .

In recent years, in the development of electronic devices and new elements using new materials, film forming apparatuses for three-dimensionally forming protective films, amorphous films, or magnetic films made of inorganic materials have been developed, and manufacturing has improved. It is now being used. The film formed by this film forming apparatus has excellent step coverage and causes little damage to the object on which the film is formed.

[0004] As such a film forming apparatus, there are a facing electrode type plasma CVD apparatus and a sputtering apparatus.

[0005]

2. Description of the Related Art FIG. 7(a) is a block diagram of a conventional opposed electrode type plasma CVD apparatus.

In FIG. 7(a), 1 is a chamber whose interior is depressurized for film formation, and 2a and 2b are installed in the chamber to which alternating current voltage/current is applied to convert the reaction gas into plasma. The counter electrode 3 is a conductive holder on which the object to be film-formed is placed, and the counter electrodes 2a, 2b are arranged so that the AC voltage/current from the counter electrodes 2a, 2b is not prevented from spreading by the holder 3. Each mounting surface is arranged perpendicularly to the plate surface. 4a and 4b are the counter electrodes 2a and 4b, respectively.
an AC power supply connected to 2b and supplying an AC voltage/current;
5 is a phase shifter that controls the mutual phase relationship of AC voltage/current applied to the opposing electrodes 2a and 2b, as shown in FIG. 7(b).
), a phase relationship in which plasma spreads throughout the opposing electrodes 2a and 2b has been experimentally investigated, and the mutual phase shift is set to approximately 75 degrees.

Next, such a counter electrode type plasma CV
Figure 3 shows how to use D equipment to form an insulating protective film on the surface of bare chips and internal leads after assembly is complete.
This will be explained with reference to (a) and (b).

FIG. 3(a) is a cross-sectional view of a semiconductor device as a film-forming object 10, showing a state after assembly is completed and before the formation of a protective film, in which a Si substrate 7 is fixed on an assembly base 6. , and this Si substrate 7 and the internal posts 8a and 8b of the external leads.
Internal leads 9a and 9b are formed by connecting these.

In this state, first, the object 10 to be film-formed is placed on the mounting surface of the holder 3 of the opposed electrode type plasma CVD apparatus shown in FIG. 7, and then the pressure inside the chamber 1 is reduced.

Next, the AC voltage/current is applied to the opposing electrodes 2a, 2.
b is applied and maintained for a predetermined time, an insulating protective film 11 is formed on the surface of the bare Si substrate 7 and the internal leads 9a, 9b, as shown in FIG. 3(b).

[0011]

[Problems to be Solved by the Invention] However, even with the plasma CVD apparatus described above, when there are many objects 10 to be film-formed at the same time, the variation in film thickness distribution becomes large, and the reproducibility also deteriorates. It's getting scarce. Note that Table 1 and FIG. 6 show the investigation results regarding the variation in film thickness distribution and reproducibility, respectively.

[0012] This poses a problem when forming the film even thinner and with higher precision.

The present invention has been made in view of such conventional problems, and provides a semiconductor manufacturing apparatus and a semiconductor device manufacturing method that can improve the uniformity and reproducibility of the film thickness distribution of a formed film. The purpose is to

[0014]

[Means for Solving the Problems] The above-mentioned problems firstly include a chamber capable of reducing pressure, an inlet for introducing a reaction gas into the chamber, an exhaust port in the chamber, a counter electrode in the chamber, A holder provided between the opposing electrodes for placing the object to be film-formed, an AC power source connected to each of the opposing electrodes, and an AC voltage supplied by the AC power source and applied to the opposing electrode. In a semiconductor manufacturing apparatus having a phase control means for adjusting mutual phase relationship, a DC detection device detects and compares DC voltages of the respective opposing electrodes, and outputs a phase control signal to the phase control means based on the result. This is achieved by a semiconductor manufacturing apparatus characterized by having a control signal output means, and secondly, after placing a film-forming object between opposing electrodes, the phase difference between the alternating current voltages applied to each of the opposing electrodes is determined. The step of forming a first film on the object to be film-formed when the DC voltages of the opposing electrodes are approximately equal by adjusting from the smaller to the larger or from the larger to the smaller; A step of forming a second film on the film formed by the first film formation when the DC voltages of the opposing electrodes are approximately equal again by adjusting the phase difference to be larger or smaller. This is achieved by a method of manufacturing a semiconductor device having the following.

[0015]

[Operation] In the plasma CVD apparatus, the inventor of the present application has
It has been experimentally found that the following relationship exists between the uniformity of the thickness distribution of the formed film and the DC voltage of each opposing electrode.

That is, normally, a DC voltage having a different negative value is generated at the opposite electrode to which an AC voltage is applied depending on the distribution of ions and electrons in the plasma. Moreover, this DC voltage value varies depending on the phase difference of the AC voltage.

[0017] Since it is presumed that the distribution of ions and electrons influences the distribution of film thickness, the correlation between DC voltage and the distribution of film thickness was investigated. Table 1 shows the experimental conditions.

[0018]

[Table 1]

[0019] Under these conditions, an experiment was conducted, and the result was shown in Fig. 4(a).
The results shown in ~(c) were obtained. Wafers 20a to 20c were used as objects to be film-formed, and Si3N4 films 21a to 21c having a target thickness of 5000 Å were formed on these wafers.

As a result, the following was found.

(1) When the DC voltages are equal, the film thickness distribution will not be uniform, but will be symmetrical with respect to the center between the opposing electrodes.

(2) Furthermore, there are two phase differences that make the DC voltages equal (in the case of experiments, about 75 degrees and about 255 degrees).
As shown in FIGS. 4(a) and 4(b), the film thickness distributions are complementary to each other. That is, in the case where the phase difference is smaller, the center part becomes thinner and the peripheral part becomes thicker. On the other hand, in the case where the phase difference is large, the center part becomes thicker and the peripheral part becomes thinner.

Based on the above research results, the phase difference is approximately 75
The film was formed continuously for 10 minutes at a temperature of 255 degrees/10 minutes at a phase difference of about 255 degrees (FIG. 4(c)). As a result, as shown in Table 1,
The variation in film thickness distribution is -1 for the target film thickness of 5000 Å.
1 to +8%, which is a significant improvement compared to -28 to +39% in the conventional case. Moreover, FIG. 6 shows the results of a reproducibility investigation conducted under the same conditions as those in Table 1, and according to FIG. 6, the reproducibility was also improved compared to the conventional case.

By the way, according to the semiconductor manufacturing apparatus of the present invention, the DC detection detects and compares the DC component of the AC voltage applied to each counter electrode, and outputs a phase control signal to the phase control means based on the result. / Since the control signal output means is provided, the phase difference can be adjusted so that the DC voltages are approximately equal as described above. As a result, the first and second films can be formed continuously at each phase difference such that the DC voltage is equal, so that the film can be formed so as to compensate for variations in film thickness at each phase difference. Finally, a film with good uniformity of film thickness distribution can be obtained with good reproducibility.

Further, according to the method of manufacturing a semiconductor device of the present invention, since the first and second films are successively formed with respective phase differences such that the DC voltages are equal, The film can be formed so as to compensate for the variation in film thickness. As a result, it is possible to finally obtain a film with good uniformity of film thickness distribution with good reproducibility.

[0026]

[Example] (1) First Example FIG. 1 shows a counter-electrode type plasma C of the first example of the present invention.
FIG. 2 is a configuration diagram illustrating a VD device.

In FIG. 1, 12 is a chamber whose interior is depressurized for film formation, and 13a and 13b are chambers 1
A counter electrode 2 is installed in which AC voltage/current is applied to convert the reaction gas into plasma, and 14 is a conductive holder on which the object to be filmed is placed. The opposing electrodes 13a and 1 are arranged so that the voltage/current is not prevented from spreading by the mounting surface of the film-forming object of the holder 14.
They are arranged perpendicularly to the plate surface of 3b. 15a,1
5b is connected to the counter electrodes 13a and 13b, respectively, and is an AC power source that supplies an AC voltage/current; 16 is each counter electrode 1;
A DC detection/control signal output means that detects the DC voltage possessed by the DC voltages 3a and 13b, compares the DC voltages, and outputs a control signal.Usually, the voltage generated between the opposing electrodes 13a and 13b due to the applied AC voltage/current is Each counter electrode 13a, 13b has a different value depending on the plasma distribution. Also, 17
is a phase shifter (phase control means) that controls the mutual phase relationship based on the DC voltage from the DC detection/control signal output means 16, and reduces the phase difference between the AC voltages applied to each opposing electrode 13a and 13b, for example. When the DC voltages of the opposing electrodes 13a and 13b become approximately equal, the phase of each AC voltage is fixed and held for a predetermined time. According to experiments, when the phase difference between the AC voltages is about 75 degrees and about 225 degrees, the opposing electrodes 13a,
The DC voltages of 13b become approximately equal.

Reference numeral 18 represents an inlet for the reaction gas, and 19 represents an exhaust port for discharging the gas used in the reaction.

As described above, according to the opposed electrode type plasma CVD apparatus of the first embodiment of the present invention, each of the opposed electrodes 1
3a and 13b, and outputs a phase control signal to the phase shifter 17 based on this result. The phase difference can be adjusted so that they are equal. This allows continuous film formation at each phase difference such that the DC voltage is equal.
A film can be formed so as to compensate for variations in film thickness due to each phase difference, and finally a film with good uniformity of film thickness distribution can be obtained with good reproducibility.

(2) Second Embodiment Next, using such a facing electrode type plasma CVD apparatus, after the assembly is completed, S is applied to the surface of the bare chip and internal leads.
A method for forming a protective film made of an i3N4 film will be described with reference to FIGS. 1, 2(a) and 2(b), and 3(a) and 3(b).

FIG. 3(a) shows the Si3N4
This is a cross-sectional view of a semiconductor device as a film-forming object 26, showing a state before film formation, in which a Si substrate 23 is fixed on an assembly base 22, and the Si substrate 23 and internal posts 24a, 24b of external leads are connected to each other. and internal leads 25a, 2.
5b is formed.

In this state, first, the object 26 to be film-formed is placed on the holder 14 of the opposed electrode type plasma CVD apparatus shown in FIG.
After placing the chamber 12, the pressure inside the chamber 12 is reduced.

Next, as shown in the outline of the control system in FIG. 2(a), the phase difference between the AC voltages applied to each of the opposing electrodes 13a and 13b is changed from the smaller to the larger by the control signal of the phase shifter 17. We will make adjustments. The DC voltage of each opposing electrode 13a, 13b is monitored by the DC detection/control signal output means 16, and when the DC voltage of each opposing electrode 13a, 13b becomes almost equal, this state is maintained for about 10 minutes and the target is set. A Si3N4 film having a thickness of about half of the film thickness is formed. At this time, the phase difference is approximately 75 degrees, and the film thickness distribution of the formed film is thinner at the center than at the periphery (FIG. 4(a)).

Next, the phase difference is adjusted to a larger value,
When the DC voltages of each counter electrode became almost equal again, this state was maintained for about 10 minutes, and the remaining film thickness was
4 Perform film formation of the film. At this time, the phase difference is approximately 225
As confirmed by experiments, the central part is thicker than the peripheral part (FIG. 4(b)). As a result, although the thickness of the Si3N4 film formed by each individual phase difference is non-uniform, in the end they complement each other exactly and the Si3N4 film 27 with a uniform thickness is formed (Fig. 4(c)).
).

According to the above investigation results, as shown in Table 1, the variation in film thickness distribution is -11 to +8% for a target film thickness of 5000 Å, compared to -28 to +39% in the conventional case. Significantly improved. In addition, Figure 6 shows the results of a reproducibility study conducted under the same conditions as those in Table 1.
According to the authors, reproducibility was also improved compared to the conventional case.

As described above, according to the method for manufacturing a semiconductor device according to the second embodiment of the present invention, films are formed successively at each phase difference such that the DC voltages are equal.
The film can be formed so as to compensate for variations in film thickness due to each phase difference. As a result, it is possible to finally obtain a film with good uniformity of film thickness distribution with good reproducibility.

In the second embodiment, the phase difference of the AC voltage is adjusted from the smaller to the larger, but it can also be adjusted from the larger to the smaller.

[0038]

As described above, the semiconductor manufacturing apparatus of the present invention detects and compares the DC voltage of each opposing electrode, and outputs a phase control signal to the phase control means based on the result. Since the control signal output means is provided, the phase difference can be adjusted so that the DC voltages are approximately equal as described above. This allows the first and second films to be formed successively at each phase difference such that the DC voltage is equal, so that the film can be formed in such a way as to compensate for variations in film thickness distribution at each phase difference. Finally, a film with good uniformity of film thickness distribution can be obtained with good reproducibility.

Furthermore, according to the method of manufacturing a semiconductor device of the present invention, since films are formed successively at each phase difference such that the DC voltage is equal, variations in film thickness at each phase difference are compensated for. A film can be formed in a complementary manner. As a result, it is possible to finally obtain a film with good uniformity of film thickness distribution with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating a counter electrode type plasma CVD apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of applying an alternating current voltage to a facing electrode type plasma CVD apparatus applied to a method of manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating the operation of the semiconductor manufacturing apparatus and the semiconductor device manufacturing method of the present invention.

FIG. 5 is a diagram illustrating an AC voltage applied to a counter electrode of the plasma CVD apparatus according to the first embodiment of the present invention and a DC voltage of each counter electrode.

FIG. 6 is a diagram for comparing and explaining the reproducibility of film formation by the method of manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating a conventional opposed electrode type plasma CVD apparatus.

[Explanation of symbols]

1, 12 chamber, 2a, 2b, 13a, 13b counter electrode, 3, 14
Holder, 4a, 4b, 15a, 15b AC power supply, 5 Phase shifter, 6, 22 Assembly base, 7, 23 Chip, 8a, 8b, 24a, 24b Internal post, 9a, 9
b, 25a, 25b internal lead, 10, 26 film-forming object, 11, 27 protective film, 16 DC detection/control signal output means, 17 phase shifter (phase control means), 18 gas inlet, 19 exhaust port, 20a ~20c wafer, 21a~21c Si3N4 film.

Claims (2)

[Claims] 1. A chamber capable of reducing pressure, an inlet for introducing a reaction gas into the chamber, an exhaust port in the chamber, a counter electrode in the chamber, and a chamber disposed between the counter electrodes.
A holder for placing the object to be film-formed, an AC power supply connected to the counter electrode, and a phase control for adjusting the mutual phase relationship of the AC voltage supplied by the AC power supply and applied to the counter electrode. The semiconductor manufacturing apparatus has a DC detection/control signal output means for detecting and comparing DC voltages of each of the opposing electrodes and outputting a phase control signal to the phase control means based on the results. Semiconductor manufacturing equipment. Claim 2: After placing a film-forming object between opposing electrodes,
The phase difference of the AC voltages applied to each of the opposing electrodes is adjusted from the smaller to the larger, or from the larger to the smaller, and when the DC voltages of the opposing electrodes become approximately equal, the film-forming object is a step of forming a first film on the top; and adjusting the phase difference to be larger or smaller, and when the DC voltages of the opposing electrodes become approximately equal again, forming the first film. a step of forming a second film on the formed film.