JP4947766B2 - Method for forming silicon-based thin film - Google Patents

Description

  The present invention relates to a method for forming a silicon-based thin film. More specifically, the present invention relates to a method of forming a silicon-based thin film having an insulating function or a barrier function on a substrate by a CVD method.

The silicon nitride film is important as a protective film or an insulating film of a semiconductor device, and a thermal CVD method or a plasma CVD (chemical vapor deposition) method is used for the formation. In the thermal CVD method, for example, a silicon nitride film is chemically vapor-grown on the substrate surface by a thermal decomposition reaction at a temperature of 750 to 800 ° C. using silane (SiH ₄ ) gas and ammonia (NH ₃ ) gas. . In the plasma CVD method, SiH ₄ gas and NH ₃ gas are used, a high-frequency electric field is applied to the reaction gas, the gas is activated using the electrical energy, and the substrate is formed at a low temperature of about 300 ° C. by plasma reaction. A silicon nitride film is chemically vapor-grown on the surface. Conventionally, the silicon nitride film formed in this way has a problem that cracks and peeling easily occur.

As a method for forming a silicon nitride film that can hardly cause cracks or peeling, for example, Patent Document 1 discloses that a halogen-based gas excited by plasma is used and etching is performed on the substrate surface under vacuum conditions to remain on the substrate. A technique is disclosed in which impurities are completely removed and uniform and fine irregularities are formed on the surface to improve the adhesion and film quality between the silicon nitride film and the substrate. Further, in Patent Document 2, a pretreatment chamber is provided in front of the film formation chamber, and the surface of the substrate is irradiated with ECR plasma in this pretreatment chamber, and moisture adsorbed on the surface of the substrate and film formation on the substrate are formed. A technique for desorbing moisture contained in a thin film is disclosed.
JP-A-5-315251 JP-A-5-331618

  However, when the method of Patent Document 1 described above is applied to a substrate on which an electronic device such as an organic EL is formed, the electronic device itself may be etched. Further, when the technique of Patent Document 2 described above is applied to the substrate, the electronic device is constantly exposed to ECR plasma when moisture is desorbed, and thus is susceptible to plasma damage. In addition, since the pretreatment chamber is provided in front of the film forming chamber, the apparatus configuration becomes large.

  The present invention has been made in view of such circumstances, and without damaging an electronic device formed on a substrate and without making the apparatus configuration large, a silicon-based thin film on the substrate. It is an object of the present invention to provide a method for forming a silicon-based thin film that can improve the adhesion of the silicon-based thin film and can form a silicon-based thin film that is less susceptible to cracking and peeling.

In order to achieve the above object, a silicon-based thin film forming method according to claim 1 is a method of forming a silicon-based thin film having an insulating function or a barrier function on a substrate K by a CVD method using ICP. In the method, first, the first thin film 11 is formed on the substrate K by plasma CVD using ICP using a gas containing hydrogen element and a gas containing silicon element as source gas, and then nitrogen element A second thin film 12 having an insulating function or a barrier function is formed on the first thin film 11 by a CVD method using ICP, using a gas containing silicon and a gas containing silicon element . In forming the two thin films 12, the substrate K is swung during the thin film formation .

The method for forming a silicon-based thin film according to claim 2 is a method of forming a silicon-based thin film having an insulating function or a barrier function on a substrate K by a CVD method using ICP. The first thin film 11 is formed on the substrate K by a plasma CVD method using ICP using a gas containing a hydrogen element and a gas containing a silicon element, and then a gas containing an oxygen element and a silicon element are formed. In forming the first thin film 11 and the second thin film 12, the second thin film 12 having an insulating function or a barrier function is formed on the first thin film 11 by a CVD method using ICP . The substrate K is rocked during the thin film formation .

  The method for forming a silicon-based thin film according to claim 2 uses HMDS gas as a gas containing silicon element used for forming the first thin film 11 and the second thin film 12.

  In the present invention, the substrate is a target to which an insulating function or a barrier function is given, and a resin film itself such as a PET (polyethylene terephthalate) film or an electronic device such as an organic EL is provided on the resin film. The one formed.

  According to the present invention, the adhesion of the silicon-based thin film to the substrate can be improved without causing damage to the electronic device formed on the substrate and without making the apparatus configuration large, and cracks and peeling This makes it possible to form a silicon-based thin film that is difficult to cause.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic front view of a sealing film forming apparatus used in the practice of the present invention, and FIG. 2 is a schematic plan view of the sealing film forming apparatus of FIG. This sealing film forming apparatus is manufactured for film forming experiments, and is different from an apparatus used in a production line in a manufacturing factory of a semiconductor device such as an organic EL substrate.

  As shown in FIG. 1, the sealing film forming apparatus 1 includes a load lock chamber 2, a robot chamber 3 connected to the load lock chamber 2, and a film forming chamber 4 connected to the robot chamber 3. The sealing film to be formed by the sealing film forming apparatus 1 is a silicon nitride film.

  The load lock chamber 2 can be isolated from the robot chamber 3 by the gate valve 21. In addition, it is connected to the vacuum pump 22 and has a substrate stocker 23 therein. The substrate stocker 23 includes support pins 24 for supporting the peripheral edge of the substrate K. Here, the organic EL element 9 is formed on the surface of the substrate K, and the size thereof is 370 mm × 470 mm.

  The robot chamber 3 includes a substrate transfer robot 31 inside. The substrate transfer robot 31 includes a motor 32, an arm 33, and a movable support base 34. The movable support base 34 is configured to be movable in the X, Y, and Z directions via the arm 33 by driving the motor 32. The movable support base 34 includes support pins 35 similar to those of the substrate stocker 23.

The film formation chamber 4 communicates with the robot chamber 3, is connected to the vacuum pump 42 via the flow control valve 41, is connected to the HMDS supply tank 44 via the flow control valve 43, and is connected via the flow control valve 45. Are connected to the N ₂ supply tank 46, and are connected to the H ₂ supply tank 52 and the Ar supply tank 53 via the flow rate control valve 51. A loop antenna 47 is provided inside the film forming chamber 4.

  The loop antenna 47 is a means for generating plasma and includes an insulating tube 48 and a conductive electrode 49. Two insulating tubes 48 are arranged in parallel in the film forming chamber 4 so as to face each other. The conductive electrode 49 is inserted into the two insulating tubes 48 and passes through the side walls facing each other of the film forming chamber 4 so as to have a substantially U shape in plan view as shown in FIG. Connected to power supply 50. The frequency of the high-frequency current 50 is preferably 13.56 MHz. The plasma to be used may be CCP, ICP, barrier discharge, hollow discharge, or the like.

  Next, a method for forming a silicon nitride film according to the present invention will be described with reference to FIGS. 3A and 3B are diagrams for explaining a step of forming a silicon nitride film according to the present invention. FIG. 3A is a schematic side view of an unsealed organic EL element substrate, and FIG. FIG. 3C is a schematic side view of the organic EL element substrate on which the second thin film is formed. FIG. 4 is a flowchart showing a procedure for forming a silicon nitride film.

The sealing film forming apparatus 1 is described as being in the initial state shown below. That is, the load lock chamber 2 is in a state where the gate valve 21 is closed, and the internal pressure of the load lock chamber 2 is atmospheric pressure. The substrate stocker 23 holds an unsealed substrate K (see FIG. 3A) on which the organic EL element 9 is formed with the element formation surface K1 facing vertically downward. In addition, the film forming chamber 4 and the robot chamber 3 are decompressed to 9.9 × 10 ⁻⁵ Pa or less by the vacuum pump 42.

  First, the vacuum pump 22 starts operating, and the load lock chamber 2 is depressurized (step S1). When the internal pressure of the load lock chamber 2 becomes almost the same as the internal pressure of the film forming chamber 4 and the robot chamber 3, the gate valve 21 is opened. Subsequently, the substrate transfer robot 31 extends the arm 33 to the load lock chamber 2 and directs the unsealed substrate K held by the substrate stocker 23 in the same posture, that is, its element formation surface K1 vertically downward. It is received on the movable support base 34 in a state. After receiving the substrate K, the substrate transport robot 31 contracts the arm 33. After the arm 33 contracts, the gate valve 21 is closed, and the substrate transfer robot 31 extends the arm 33 to the film forming chamber 4 as shown by a two-dot chain line in FIG. Set (step S2).

When the substrate K is set in the film forming chamber 4, the sealing film forming process is started. That is, by opening the flow valve 51, a mixed gas of H ₂ gas and Ar gas is introduced into the film forming chamber 4. At the same time, the HMDS gas is introduced into the film forming chamber 4 by opening the flow valve 43. By adding Ar gas, the dissociation reaction can be performed with relatively low energy plasma. At this time, the introduction speed of each gas is preferably 20 sccm to 40 sccm for the mixed gas of H ₂ gas and Ar gas, and 3 sccm to 5 sccm for the HMDS gas (step S3). Subsequently, a high frequency current is passed from the power supply 50 to the loop antenna 47. As a result, plasma is generated around the loop antenna 47. The plasma power at this time is preferably 5 kW to 10 kW (step S4). A surface reaction is performed on the surface of the substrate K, and the first thin film 11 is formed so as to cover the organic EL element 9 as shown in FIG.

After the predetermined time T1 has elapsed, the introduction of the mixed gas of H ₂ gas and Ar gas is stopped by closing the flow valve 51, and the N ₂ gas is introduced into the film forming chamber 4 by opening the flow valve 45. Note that NH ₃ gas may be introduced instead of N ₂ gas. At the same time, the introduction rate of the HMDS gas is adjusted by the flow valve 43. At this time, the introduction speed of each gas is preferably 20 sccm to 40 sccm for N ₂ gas and 3 sccm to 5 sccm for HMDS gas (step S5). Subsequently, a high frequency current is supplied from the power source 50 to the loop antenna 47 so that the plasma power is 4 kW to 8 kW. As a result, plasma is generated around the loop antenna 47 (step S6). A surface reaction is performed on the surface of the substrate K, and a second thin film 12, that is, a silicon nitride film is formed so as to cover the first thin film 11, as shown in FIG. After the predetermined time T2 has elapsed, the introduction of N ₂ gas is stopped by closing the flow valve 45, and the introduction of HMDS gas is stopped by closing the flow valve 43 (step S7).

As described above, first, H ₂ gas, Ar gas, and HMDS gas are used as source gases, the first thin film 11 is formed on the substrate K by plasma CVD, and then N ₂ gas and HMDS gas are used. Then, the second thin film 12 which is a silicon nitride film is formed. Since HMDS gas is used as the raw material gas, there is no risk of explosion and excellent safety.

  It has been found that the first thin film 11 formed in the previous process (steps S1 to S4) has good adhesion. By interposing the first thin film 11 between the substrate K and the second thin film 12, the adhesion between the substrate K and the second thin film 12 is improved. As a result, the second thin film 12 is not cracked or peeled off. It becomes difficult to occur and can be reliable with little performance variation. Unlike the conventional method, the method of the present invention does not use an etching process or the like, and therefore does not damage electronic devices such as the organic EL element 9. Further, as the first thin film 11 has a function of protecting electronic devices such as the organic EL element 9 from plasma energy as it is chemically vapor-grown on the substrate K, damage to the electronic device due to plasma energy is prevented. Less is enough. Further, since the formation of the first thin film 11 and the formation of the second thin film 12 are performed in the same chamber (deposition chamber 4), the apparatus structure does not become large.

In forming the second thin film 12 in the subsequent steps (steps S5 to S7), a gas containing an oxygen element may be used instead of a gas containing a nitrogen element such as N ₂ gas or NH ₃ gas. In this case, the second thin film 12 becomes a silicon oxide film, and has an excellent insulating function or barrier function like the silicon nitride film.

  In order to prevent the organic EL itself from being damaged by heat on the substrate on which the organic EL device is formed, the temperature at the time of forming each film is preferably 100 ° C. or less. During the formation of the sealing film described above, the movable support base 34 may be swung in the X direction at a predetermined cycle. Thereby, a uniform film without unevenness can be obtained.

  When the formation of the second thin film 12 is completed, the gate valve 21 is opened in the load lock chamber 2, and the substrate transfer robot 31 contracts the arm 32 and then extends the load lock chamber 2. Then, the sealed substrate K is transferred to the substrate stocker 23, and the substrate transport robot 31 contracts the arm 33. After the arm 33 contracts, the gate valve 21 is closed, the load lock chamber 2 is returned to atmospheric pressure and opened (step S8), and then the substrate K on which the sealing film has been formed can be taken out (step S9). .

In the sealing film forming apparatus 1, a silicon nitride film was formed by the following methods A and B. In the method A, the second thin film 12 was formed after the first thin film 11 was formed as shown in the above embodiment. In the method B, the second thin film 12 was formed without forming the first thin film 11.
(A) The film forming conditions are shown below.
Pressure in the film formation chamber 4 when forming the first thin film: 3 Pa
Introduction speed of mixed gas of H ₂ gas and Ar gas: 30 sccm
HMDS gas introduction speed: 3 sccm
Plasma power: 9kW
Pressure in the film forming chamber 4 when forming the second thin film: 3 Pa
N ₂ gas introduction rate: 30 sccm
HMDS gas introduction speed: 3 sccm
Plasma power: 6kW
(B) The conditions for forming the second thin film are the same as in A, and the first thin film is not formed (no hydrogen plasma treatment).

  Table 1 shows a comparison result between the film formed of A and the film formed of B. When the first thin film was formed as in A, it was not peeled off even when immersed in water or by ultrasonic cleaning. However, when the first thin film was not formed as in B, it was immersed in water. Cracking occurred just by soaking, and it almost peeled off after ultrasonic cleaning.

○：剥がれ無し
△：小さい剥がれ有り
×：剥がれ有り

○: No peeling △: Small peeling ×: There is peeling

  As mentioned above, although embodiment of this invention was described, embodiment disclosed above is an illustration to the last, Comprising: The scope of the present invention is not limited to this embodiment. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a front schematic diagram of a sealing film forming device used for carrying out the present invention. FIG. 2 is a schematic plan view of the sealing film forming apparatus of FIG. 1. It is a figure for demonstrating the formation step of the silicon nitride film by this invention. It is a flowchart which shows the procedure which forms a silicon nitride film.

Explanation of symbols

9 Organic EL elements (electronic devices)
11 1st thin film 12 2nd thin film K substrate

Claims (3)

In a silicon-based thin film forming method of forming a silicon-based thin film having an insulating function or a barrier function on a substrate by a CVD method using ICP ,
First, as a source gas, a gas containing hydrogen element and a gas containing silicon element are used, and a first thin film is formed on the substrate by a plasma CVD method using ICP .
Next, using a gas containing nitrogen element and a gas containing silicon element, a second thin film having an insulating function or a barrier function is formed on the first thin film by a CVD method using ICP ,
A method of forming a silicon-based thin film, wherein the substrate is swung during the formation of the first thin film and the second thin film . In a silicon-based thin film forming method of forming a silicon-based thin film having an insulating function or a barrier function on a substrate by a CVD method using ICP ,
First, as a source gas, a gas containing hydrogen element and a gas containing silicon element are used, and a first thin film is formed on the substrate by a plasma CVD method using ICP .
Next, a second thin film having an insulating function or a barrier function is formed on the first thin film by a CVD method using ICP using a gas containing an oxygen element and a gas containing a silicon element ,
A method of forming a silicon-based thin film, wherein the substrate is swung during the formation of the first thin film and the second thin film . As a gas containing silicon element used for forming the first thin film and the second thin film, H
The method for forming a silicon-based thin film according to claim 1 or 2, wherein MDS gas is used.

Images