JP3453720B2 - Combinatorial plasma CVD equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently finding out components and fabrication conditions of device constituents in a short time, and further, plasma CVD capable of efficiently finding components and fabrication conditions of device constituents in a short time. It relates to the device.

[0002]

2. Description of the Related Art In recent years, devices in which a large number of thin films having different properties are bonded have been used more and more and required performances have become higher. For example, amorphous solar cells have attracted attention as solar cells that can be manufactured at low cost and have a large area. This amorphous solar cell is a thin film solar cell that can be manufactured at a low temperature of 300 ° C. or lower, and has the advantage of essentially low cost and energy saving.
However, in the conventional pin-type amorphous silicon solar cell, blue light is mostly absorbed in the p-type window layer, and the generated carriers are easily recombined. Therefore, in the amorphous solar cell, the blue sensitivity is improved. Was a problem in mass production.

In order to solve this problem, the present inventors have made the p- or n-type inducing layer generated by the field effect take on the role of the p- or n-type doping layer. Type solar cell structure was proposed. In this field-effect solar cell structure, since the electric field exists even at the interface between the insulator and the amorphous silicon, the carriers generated in the inducing layer are rapidly and spatially separated by the interface, which is significantly larger than the conventional type. High quantum efficiency can be expected.

[0004]

However, since the structure of the field-effect solar cell is completely different from that of the conventional solar cell, much time and development efforts are required in terms of material, process, design, etc. Will be required. In particular, since it is necessary to apply an electric field to the amorphous silicon layer through the insulating film to form an induction layer, a good quality insulator and amorphous silicon interface are indispensable. Further, the insulating film is required to have high transparency and high resistivity. In addition to such material and process aspects, also in device design, such as optimization of mask pattern to reduce series resistance, optimization of film thickness of each layer, improvement of quality of amorphous silicon film, light irradiation deterioration countermeasures, etc. There are important challenges.

In this type of thin film junction device, in order to obtain a device structure that solves the above problems, an extremely large number of experiments and their verifications are required. In view of such circumstances, an object of the present invention is to provide a combinatorial thin film forming method which can realize optimization of a device structure extremely efficiently and a combinatorial plasma CVD apparatus using this method.

[0006]

[0007]

[0008]

[0009]

[0010]

[0011]

[Means for Solving the Problems] To achieve the above object
The combinatorial plasma CVD apparatus of the present invention is a plasma CVD apparatus that deposits a reaction product of a gas activated by plasma on a substrate to form a thin film, and includes a fixed mask that is placed in close contact with the substrate and a fixed mask. A movable mask disposed so as to cover the mask is provided, and the film formation region is selected by moving the movable mask and rotating the substrate with which the fixed mask is in close contact.

The combinatorial plasma CVD apparatus preferably comprises a linear movement mechanism for linearly reciprocating the movable mask and a rotary drive mechanism for rotating the fixed mask.

Preferably, the fixed mask has a shape in which a plurality of openings are arranged in a matrix in a rectangular shape, a rectangular shape, a circular shape, etc., and the movable mask allows a row or a column of the plurality of openings arranged in the matrix. It has an opening.

The combinatorial plasma CVD of the present invention
According to the apparatus, two masks , a fixed mask and a movable mask, are used, and each of them is rotated and moved linearly to move the composition while switching the film forming gas or synchronizing with film forming conditions such as plasma conditions. It is possible to extremely efficiently form many kinds of thin films under different manufacturing conditions.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In order to optimize the device structure of a device formed by joining a plurality of films, a huge number of samples with different film forming conditions or film compositions were prepared, and the characteristics of these samples were measured. It is necessary to measure all of the above and obtain the optimum conditions. In the film forming method and apparatus using a vacuum device, it takes a long time and a large amount of energy (vacuum) to draw a vacuum in order to reach the degree of vacuum required for film formation after setting the substrate on which the sample is formed in the vacuum device. (Electric power for pumps, etc.) is required. With the conventional film forming method and apparatus using the vacuum device, only one film forming condition or film composition can be formed by one evacuation. Therefore, in order to prepare a huge number of samples with different film forming conditions or film compositions,
Each time it took a huge amount of time and energy.
The thin film forming method and apparatus of the present invention, by a single evacuation,
A thin film forming method and apparatus capable of producing a plurality of samples having different film forming conditions or film compositions, that is, a combinatorial thin film forming method and a combinatorial plasma CVD apparatus.

Preferred embodiments of a combinatorial thin film forming method and a combinatorial plasma CVD apparatus according to the present invention will be described below with reference to FIGS. Figure 1
Shows the configuration of the main part of the plasma CVD apparatus in this embodiment. In the figure, 1 is a chamber into which a reaction gas is introduced, 2a is an anode electrode, and 2b is a cathode electrode. The substrate 3 is supported by a rotatable shaft 4 as described later, and a fixed mask 5 is fixed thereon. Reference numeral 6 denotes a movable mask which is set on the fixed mask 5 so as to be removable.

Reference numeral 7 denotes a pulley fixed to the end of the shaft 4 protruding outside the chamber 1, 8 a stepping motor, 9 a pulley fixed to the output shaft of the stepping motor 8, and 10 a winding between the pulley 7 and the pulley 9. It is a mounted timing belt. The stepping motor 8 has its drive circuit 1
The drive is controlled by the control unit 12 via the control unit 1. The control unit 12 can be appropriately operated by the operation unit 13.

Reference numeral 14 is a rod for supporting the movable mask 6,
Reference numeral 5 is a drive unit that linearly reciprocates the rod 14, and 16 is a stepping motor. Stepping motor 16
Is controlled by the control unit 12 via the drive circuit 17. These drive control parameters and the like can be set and input by the operation unit 13.

A high frequency voltage is applied between the anode electrode 2a and the cathode electrode 2b, and the discharge gas generated therein activates the reaction gas in the chamber 1. An exhaust device (not shown) is connected to the chamber 1, and the pressure of the reaction gas can be controlled. The control unit 12 can control the driving timing or speed of the substrate 3, that is, the fixed mask 5 or the movable mask 6, according to the film forming conditions such as the applied voltage, the reaction gas composition, the reaction gas pressure, or the thin film growth temperature.

Here, the fixed mask 5 is set in close contact with the substrate 3 on which the film is to be formed, as shown in FIG. In this example, a lattice-shaped mask in which a plurality of square openings are arranged in a square shape is used. In plasma CVD performed under a pressure of about 0.1 Torr, so-called mixing between adjacent thin films due to plasma wraparound cannot be ignored. The fixed mask 5 is brought into close contact with the surface of the substrate 3 so as to partition the lattice-shaped film forming region and prevent such mixing.

The movable mask 6 is, as shown in FIG.
It is supported by the tip of the rod 14. The gap (gap) between the fixed mask 5 and the movable mask 6 is set to about 0.1 mm in this example. Vacuum degree of plasma CVD (0.1 to 0.
In 05 Torr), since the plasma wraparound distance is almost proportional to this distance, the distance between the fixed mask 5 and the movable mask 6 is set according to the distance between the openings of the fixed mask. The movable mask 6 of this example has a rectangular opening 6a as shown in the drawing, and the opening 6a limits the lattice-shaped film formation region set by the fixed mask 5. For example, the opening 6a is made to correspond to the region range of one row of the lattice, and the remaining region range is hidden from the plasma discharge.

The fixed mask 5 and the movable mask 6 are each coated with a predetermined substance. These masks are sputtered in the plasma and their forming materials can adhere to the deposition substrate. Therefore, a material which can be attached to or mixed with the substrate is coated in advance. For example, when depositing amorphous silicon, amorphous silicon is coated.

Next, an embodiment of the method for forming a combinatorial thin film of the present invention, which is carried out by using the combinatorial plasma CVD apparatus having the above-mentioned constitution of the present invention, will be described in principle and schematically with reference to FIGS. 4 and 5.

In FIG. 4A, a row of a plurality of openings (referred to as an opening array) in which the movable mask 6 is arranged in a square shape of the fixed mask with respect to the fixed mask 5 set on the substrate 3. Move from the direction (called the first direction). As shown in FIG. 5A, the opening 6a of the movable mask 6 is positioned corresponding to the first row (row A) of the opening arrangement of the fixed mask. In this manner, plasma CVD is performed under a predetermined film forming condition to form a thin film with the movable mask 6 limiting the opening for plasma to the line A. After the film formation in row A is completed, the opening 6a of the movable mask 6 is formed in
Move to the row and change the film forming conditions to form a film. As shown in the drawing, a thin film is formed by sequentially changing the film forming conditions of row A, row B, row C, and row D. In this example, four types of thin films with different film forming conditions are formed.

In FIG. 5B, the movable mask 6 is moved from the column direction (called the second direction) of the opening arrangement of the fixed mask which is orthogonal to the first direction. In this case, in order to change the approach direction of the movable mask 6 with respect to the fixed mask 5,
By driving the substrate 3 to rotate 90 ° by the stepping motor 8 (FIG. 4 (B)), it is possible to accurately perform the process.

As shown in FIG. 5B, the openings 6a of the movable mask 6 are arranged in the first direction in the opening arrangement of the fixed mask from the second direction.
It is positioned corresponding to the row number (row a). Thus, the thin film is formed by performing the plasma CVD under the predetermined film forming condition on the column a limited by the movable mask 6. After the film formation in the row a is completed, a thin film is formed while sequentially changing the film formation conditions of the row b, the row c, and the row d as illustrated. In this example, a total of 16 kinds of combined thin films are formed in combination with the case of performing from the first direction.

Thus, according to the present invention, the fixed mask 5
By using two masks, the movable mask 6 and the movable mask 6, each of which is moved by the rotating mechanism and the moving mechanism while being synchronized with the film forming conditions, a combination of various kinds of thin films having different compositions and manufacturing conditions can be formed very efficiently. be able to.

[0028]

EXAMPLES Next, specific examples of the present invention will be described. FIG. 6 shows the combinatorial plasma C of the present invention.
An example of a combinatorial library having a semiconductor / dielectric two-layer structure manufactured by the VD method is shown. In this example, first, on a glass substrate with a transparent conductive film, a-SiN: H is provided for each row (X direction) of the opening arrangement of the fixed mask.
(Amorphous silicon nitride) is deposited by changing the film formation time, and then a-Si: H is formed for each row of the array of openings (Y direction).
(Amorphous silicon) is deposited by changing the film formation time. As a result, a combinatorial library having a two-layer structure of a-SiN: H / a-Si: H, which is the basis of the thin film transistor structure, could be produced. Note that the graph of FIG. 6A shows the film formation time, and the graph of FIG.
The graph of is represented by the film thickness.

The procedure for preparing the above combinatorial library is as follows. Substrate Setting First, the glass substrate 3 with ITO (Indium Tin Oxide) is washed with acetone, ethanol, and pure water. The substrate 3 is placed on the anode electrode 2a, and the fixed mask 5 is overlaid thereon. The fixed mask 5 is fixed to the anode electrode 2a with a screw. As a result, the substrate 3 can be firmly attached to the anode electrode 5, heat conduction can be ensured, and displacement of the substrate during the process can be prevented. The lid of the chamber 1 is closed and vacuum exhaust is performed by a rotary pump and a turbo molecular pump. When the degree of vacuum reaches about 10 ^-5 Torr, the anode heater is energized to remove residual water in the chamber 1 (water vapor in the air adhering to the inner wall of the chamber while the atmosphere is open), and the substrate 3 is heated to 300 ° C. Raise the temperature. At the same time, the silicon heater around the outer wall of the chamber is also heated to about 120 ° C.
This state is maintained for about 6 hours.

Formation of a-SiN: H insulating layer (see FIG. 7)
(A), lines A2 to A7). First, the temperature of the substrate 3 is set to 380 ° C. with the movable mask 6 in a state where the entire area of the substrate 3 is covered. Subsequently, the semiconductor gas exhaust rotary pump and the mechanical booster pump are started. In this chamber 1, a pump system for exhausting the atmosphere and a pump system for exhausting semiconductor gas are separately provided, and the exhaust system is switched immediately before the semiconductor gas is introduced.

The exhaust valve on the turbo molecular pump side is fully closed, and the chamber 1 is vacuum-sealed. The NH ₃ (ammonia) flow rate is set to 25 sccm (cm ³ / min) and the gas is introduced into the chamber 1. Chamber pressure is 50mTorr
When it rises to (6.66 Pa), fully open the exhaust valve on the mechanical booster pump side. The flow rate of SiH ₄ (silane) is set to 1 sccm, the gas is introduced into the chamber 1, and the opening / closing amount of the exhaust valve is adjusted (differential exhaust) to adjust the chamber internal pressure to 75 mTorr. A high frequency of 140 mW / cm ² of 13.56 MHz (industrial frequency defined by International Radio Law) is applied to the cathode electrode 2b to generate plasma. In this way about 3
A film of a-SiN: H is formed on the movable mask 6 for 0 minutes to form a coating layer.

Next, the high frequency is turned off, the coating film formation is stopped, and the window 6a of the movable mask 6 is opened as shown in FIG.
Then, the combinatorial film formation is started by moving so as to overlap the line A2. A film is formed on the A2 row region for 20 minutes.
The film is not formed on the A1 row region. High frequency is OF
F, the window portion 6a of the movable mask 6 is A3 in FIG.
Move to overlap the line. A film is formed on the A3 row region for 40 minutes. The same procedure is repeated to form films for the A4 to A7 row regions for 60 minutes, 80 minutes, 100 minutes, and 120 minutes, respectively. Stop the flow of reaction gas and fully open the exhaust valve on the mechanical booster pump side.

Film formation of a-Si: H (amorphous silicon) (FIG. 7A, columns B2 to B7). The movable mask 6 is retracted to separate from the anode electrode 2a. The anode electrode 2a is rotated 90 °. The movable mask 6 is moved onto the anode electrode 2a so that the entire area of the substrate 3 is covered. The flow rate of SiH ₄ (silane) is set to 10 sccm, and the SiH ₄ (silane) is introduced into the chamber 1. The opening / closing amount of the exhaust valve is adjusted (differential exhaust) to adjust the chamber internal pressure to 30 mTorr. A high frequency of 13.56 MHz and 50 mW / cm ² is applied to the cathode electrode 2b to generate plasma. A film of a-Si: H is formed on the movable mask 6 for about 30 minutes to form a coating layer.

The high frequency is turned off, the coating film formation is stopped, and the opening 6a of the movable mask is changed to B2 in FIG. 7 (A).
Move to overlap the row. Start combinatorial film formation. A film is formed on the B2 row region for 10 minutes. In addition,
No film is formed on the B1 row region. The high frequency is turned off, the slits of the movable mask are moved so as to overlap the row B3 in FIG. 7A, and film formation is performed for 20 minutes on the row B3 region. The same procedure is repeated to form films on the B4 to B7 row regions for 30, 40, 50 and 60 minutes, respectively. Stop the flow of reaction gas and fully open the exhaust valve on the mechanical booster pump side. Turn off the anode heater and wait until the temperature drops below 100 ° C.
Meanwhile, the residual NH ₃ and SiH ₄ in the pipe are exhausted.

Pure Argon (Ar) in Reaction Gas Pipe
Cleaning with NH ₃ pipe is filled with Ar at 1 kgf / cm ² , evacuated to a high vacuum with a mechanical booster pump, and Ar is filled again. Repeat this 3 times. The same work as above is performed on the SiH ₄ pipe. ₃₀ scc for NH ₃ piping
20 sccm of Ar is passed through the SiH ₄ pipe for 15 minutes to clean the inside of the mass flow controller. 1 kgf / cm ² of Ar is sealed in each pipe, and the cleaning is completed. About 10 minutes after starting the turbo molecular pump, fully open the valve on the mechanical booster pump side. Fully open the valve on the turbo molecular pump side, and put it in an ultra-high vacuum exhaust state.

After the valve on the side of the electrode vapor deposition turbo molecular pump is fully closed, the turbo molecular pump is stopped. Purge the chamber with dry N ₂ gas. The combinatorial library is taken out, and the library and the mask for electrode formation are fixed on a metal support plate. It is installed in a vacuum vapor deposition chamber to deposit Al source / drain electrodes. The electrodes are 6 × 6 as shown in FIG.
It is formed only in the area. The remaining region is subjected to film quality evaluation of a-Si: H and a-SiN: H.

In this example, 36 kinds of samples having different combinations of film thicknesses were prepared by the combinatorial thin film forming method and the combinatorial plasma CVD apparatus of the present invention.
It was possible to manufacture on one substrate in one step (from setting the substrate in the vacuum device to taking out the film-formed substrate). That is, in order to obtain these 36 types of samples by the conventional method, a step of producing each device using 36 substrates is required. Therefore, by using the combinatorial thin film forming method and the combinatorial plasma CVD apparatus of the present invention, the development efficiency of semiconductor elements can be significantly improved. Here, FIG.
The film thickness dependence of the threshold voltage of the thin film transistor produced using the combinatorial thin film forming method and combinatorial plasma CVD apparatus of the present invention is shown. As is clear from the figure, it is possible to clearly understand how the threshold value changes in accordance with the changes in the amorphous silicon film thickness and the amorphous silicon nitride film thickness.

Further, FIG. 10 shows a combinatorial thin film forming method and combinatorial plasma C according to the present invention.
The example of the field effect solar cell produced using the VD apparatus is shown. In this example, a glass plate is used as a substrate and a transparent conductive film (ITO) is used as a gate electrode. Amorphous silicon nitride films and amorphous silicon films were formed under various conditions on the transparent conductive film, and the device structure and the manufacturing process could be optimized. The characteristics of the field-effect solar cell manufactured under the optimized conditions were improved as compared with the conventional solar cell, and the optimized conditions of the field-effect solar cell could be understood.

[0039]

As can be understood from the above description, the use of the combinatorial thin film forming method and the combinatorial plasma CVD apparatus of the present invention is extremely efficient in obtaining the optimum conditions for the device structure of this type of junction device. Will be achieved. As a result, the number of experiments can be greatly saved, and a substantial cost reduction can be expected. Further, there is an advantage that the quality can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a main configuration of an embodiment of a combinatorial plasma CVD apparatus of the present invention.

FIG. 2 is a perspective view showing a fixed mask in an embodiment of the combinatorial thin film forming method of the present invention.

FIG. 3 is a perspective view showing a movable mask in an embodiment of the combinatorial thin film forming method of the present invention.

FIG. 4 is a perspective view schematically showing the principle of the combinatorial thin film forming method of the present invention.

FIG. 5 is a plan view schematically showing the principle of the combinatorial thin film forming method of the present invention.

FIG. 6 is a diagram showing an example of a combinatorial library having a semiconductor / dielectric two-layer structure in an example of the present invention.

FIG. 7 is a plan view showing a fixed mask and a movable mask according to an embodiment of the present invention.

FIG. 8 is a plan view showing a vapor deposition range of source / drain electrodes in an example of the present invention.

FIG. 9 is a diagram showing film thickness dependence of a threshold voltage of a thin film transistor in an example of the present invention.

FIG. 10 is a schematic diagram showing a configuration of a field effect solar cell according to an example of the present invention.

[Explanation of symbols]

1 chamber 2a Anode electrode 2b cathode electrode 3 substrates 4 axes 5 fixed mask 6 movable mask 7,9 pulley 8,16 stepping motor 10 Timing belt 11, 17 Drive circuit 12 Control unit 13 Operation part 14 rod 15 Drive

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Patent 3018000 (JP, B2) Patent 3018001 (JP, B2) Hideomi Koinuma, Nobuyuki Matsumoto, Combinatorial Chemistry of Inorganic Materials, Chemistry, 1998, Vol. 53, No. 4, p. 70-71 X. -D. Xiang, et al, A Combinatory Approch to Materials Discovery, SCIENCE E, June 23, 1995, Vol. 268, p. 1738-1740 X. -D. Xiang, et al, Identification and optimization of a advanced phosphorus using combinatorial libraries, Appl. Phys. Lett. , June 23, 1997, Vol. 70, p. 3353-3355 (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 14/00-16/56 C30B 1/00-35/00 H01L 21/203-21/205 JISST file (JOIS)

Claims (3)

(57) [Claims] 1. Reaction of gas activated by plasma
Plasma CVD to deposit a product on a substrate to form a thin film
A fixed mask that is placed in close contact with the substrate, and the fixed mass.
And a movable mask that is placed over the mask.
For moving the disk and rotating the substrate with the fixed mask in close contact
Therefore, a combinato characterized by selecting a film formation region
Real plasma CVD equipment . 2. A straight line for linearly reciprocating the movable mask.
Rotate the moving mechanism and the anode electrode that mounts the substrate.
And a rotation drive mechanism for causing the rotation.
1. The combinatorial plasma CVD apparatus according to 1 . 3. The fixed mask has a plurality of openings in a square shape.
Shapes that are arranged in a matrix, such as circular, rectangular, or circular
A plurality of movable masks arranged in the above matrix.
Feature openings that allow for rows or columns of
The combinatorial plasma according to claim 1, characterized in that
CVD equipment .