JPS63473A - Formation of thin film - Google Patents

Abstract

PURPOSE:To control the compsn. of a thin film in a short period and to form the prescribed thin film by calculating the refractive index and attenuation coefft. of the thin film from the thickness of the thin film formed on a substrate and the refractive index and transmittivity synthesizing the refractivity and transmittivity of the thin film and substrate. CONSTITUTION:O2 and Ar are introduced from gas introducing pipe 106, 107 into a chamber 105 in a reduced pressure state and a target 102 consisting of, for example, Te is sputtered to form the thin film TeOx (0<x<2) on the rotating substrate 108. The thin film is deposited to a crystal resonator diaphragm 111 housed in a crystal resonator monitor head 110 and the change signal of the natural frequency thereof is fed to a sputter speed controller 112 which controls a power source 113 until said signal coincides with a set value. On the other hand, the reflectivity and transmittivity fluctuating with the formation of the thin film is measured by a reflectivity measuring instrument 114 having a light emitting part 115 and a light receiving part 116 and are fed together with the film thickness signal from said speed controller 112 to an arithmetic circuit 119 which calculates the refractive index (n) and attenuation constant (k) of the thin film. The calculated refractive index and attenuation factor are compared with the set values by a comparator 128 and the partial pressure ratio of Ar and O2 is controlled by a partial pressure controller 120.

Description

Detailed Description of the Invention: The composition of the thin film is controlled by increasing the gas pressure of O2 or O2, or by decreasing the partial pressure ratio of O2 or the gas pressure of O2 if it is small. Thin film forming method described in section.

3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a method for forming a thin film that enables control of the composition of the formed thin film.

BACKGROUND OF THE INVENTION In recent years, vacuum evaporation and sputtering have been positioned as the main methods for forming thin films, and have become indispensable techniques for forming thin films for semiconductors, optical memory disks, thin film magnetic heads, and the like. Here, we will discuss an example of thin film formation using TeO (o < x < 2), which is a typical recording film for optical memory disks.
I will explain about it. Figure 3 shows a Te○ thin film on a substrate 308.
shows a configuration diagram when forming by reactive sputtering method. In the figure, 301 is a sputter gun, which is mainly composed of a sputter target 302, a supporting metal plate 303, and a magnet 304. The sputter target 302 is Te, and gas inlet pipes 306 and 307 are installed in the chamber 306 in a reduced pressure state with a partial pressure ratio of Ar, which is an inert gas, and O2, which is a reactive gas, to 3/2, for example.
A thin film of TeO is formed on the rotating substrate 30B. The sputtering speed at this time is controlled based on a signal from a crystal oscillator monitor head 310 housing a quartz crystal oscillator plate 311 using a quartz crystal oscillator method. The disc characteristics of the TeO material that is the recording film vary greatly depending on its composition. Therefore, it is necessary to analyze the composition of the formed thin film using methods such as molecular spectroscopy, but there is a problem in that it takes a long time to obtain the results.

Another method is to determine whether the composition is as desired by completing a disk and measuring its characteristics, but there are still many steps required before completing a disk and measuring its characteristics. It takes time. Furthermore, it is often difficult to determine in which direction the composition has shifted based only on the disk characteristics.

The present invention solves the above-mentioned problems, and aims to provide a thin film forming method that makes it possible to control the composition of the thin film to be formed in a short time and realizes the formation of a desired thin film. be.

Means to Solve the Problems The present invention, when forming a thin film on a substrate, measures the thickness of the thin film formed on the substrate and the combined reflectance and transmittance of the thin film and the substrate in-process. After calculating the refractive index n and extinction coefficient k of the thin film using the three types of measurement signals,
This calculation @ refractive index n with at least one of n and k set in advance. , extinction coefficient k. The thin film forming conditions are controlled so that the

If the composition of the working thin film differs, the optical constants of the thin film, that is, the refractive index n and the extinction coefficient will also differ.

In the in-process of forming a thin film on a substrate, the present invention includes:
By measuring the thickness of the thin film and the combined reflectance and transmittance of the thin film and the substrate, we can determine the refractive index n and extinction coefficient k of the thin film.
is calculated by an arithmetic circuit, and the refractive index n of the thin film is calculated using these n and k as a reference. and extinction coefficient k. The desired thin film composition can be achieved by controlling the thin film formation conditions so that it approaches
This will enable it to be maintained.

EXAMPLES Examples of the present invention will be described below by taking the production of a TeOx thin film as an example.

(Example 1) FIG. 1 is a block diagram when a TeO thin film is produced by a reactive sputtering method based on the present invention.

In the figure, 101 is a sputter gun, and this sputter gun includes a sputter target 102 made of To, and a support metal plate 10 to which the sputter target 102 is brazed.
3. It mainly consists of a rotating magnet 104 which is housed under the supporting metal plate 103. Gas introduction pipes ion, 107 to 02 and Ar are introduced into the chamber 106 which is in a reduced pressure state. Sputter target 10 made of To
The To atoms or molecules sputtered from 2 combine with 02 in the chamber 10B, and the Te atoms or molecules sputtered from 02 are attached to the rotating substrate ios.
A thin film of O (0<x<2) is formed. Note that a shutter 109 is interposed between the sputter gun 101 and the substrate 10B, and the deposition of a thin film on the substrate 108 is started by opening and closing the shutter 109.
Regulate termination. The sputtering speed is determined by the crystal oscillator method. That is, a thin film is deposited on a crystal oscillator plate 111 housed in a quartz crystal oscillator monitor head 11o, and a signal representing a change in its natural frequency is sent to a quartz crystal oscillator sputtering speed controller 11.
2, and the sputtering power source 113 is feedback-controlled so that the sputtering speed vc set in the crystal oscillator sputtering speed controller 112 matches the actual sputtering speed ■, and the sputtering speed V is integrated over time t. The thickness signal d should also be output. A reflectance measuring device 114 equipped with a light emitting section 116 and a light receiving section 116 is installed above the substrate 10B, and a transmittance measuring device 117 equipped with a light receiving section 118 is installed below. The film thickness signal from the crystal oscillator sputtering speed controller 112, the reflectance signal from the reflectance measuring device 114, and the transmittance at the same point in time during thin film formation. Three transmittance signals from the measuring device 117 are input to an arithmetic circuit 119 to calculate the refractive index n and extinction coefficient k of the thin film.

Table 1 shows the relationship between the TeO thin film value, refractive index n, and extinction coefficient. As the X value increases and becomes Tea2rich, the refractive index n decreases and the extinction coefficient also decreases. Therefore, the refractive index n obtained in a thin film having a reference composition and set in advance. The comparator 128 compares the refractive index n with the refractive index n calculated by the arithmetic circuit.

If the calculated refractive index n is larger than the preset refractive index n0, from the relationship in Table 1, the thin film being formed has a smaller X value of the TeO process than the reference thin film, and the To
It turns out that it is rich.

Therefore, the partial pressure controller 20 feedback-controls the 02 flow rate control valve 121 and the Ar flow rate control valve 122 so that the ratio of 02 in the partial pressure ratio of Ar and ○ becomes larger, and the thin film composition is shifted to the Te03rich side. The refraction in is based on the refractive index n. Try to get it close to. Conversely, the calculated refractive index n is the preset refractive index n.
If it is smaller than 0, the X value of TeOx is larger than the standard and becomes Tea2rich, so feedback control is performed to reduce the partial pressure ratio of 02,
The thin film composition is shifted to Te rich fA'l.

Here, we have explained the control of thin film composition based on the refractive index n.
It is also possible to control the thin film composition in a similar manner using the extinction coefficient k of the thin film. That is, when the extinction coefficient k calculated by the arithmetic circuit 119 is larger than the preset extinction coefficient 0, the thin film being formed has Teo! lower than the reference thin film from the relationship shown in Table 1. The X value of 'f@
It turns out that it is rich. Therefore, the partial pressure controller 120 feedback-controls the 02 flow rate control valve 121 and the Ar flow rate control valve 122 so that the ratio of 02 becomes larger in the partial pressure ratio of Ar and 02, thereby shifting the thin film composition to the Te02 rich side. Conversely, the calculated extinction coefficient k is the preset extinction coefficient k. , the Te0xOX value is larger than the reference and Too2r
ich, feedback control is performed to reduce the partial pressure ratio of 02, and the thin film composition is changed to Te
Shift to the rich side.

With this control as described above, feedback control is applied so that the composition of the formed thin film approaches the reference composition in the in-process of thin film formation, and it becomes possible to obtain a desired thin film composition. Note that in this control, it is desirable to control the main valve 124 connecting the chamber 106 and the exhaust system 123 so that the total pressure inside the chamber 105 is always the same.

(Example 2) FIG. 2 is a configuration diagram when a TeO thin film is produced by a thin film empty deposition method based on the present invention. In the figure, reference numeral 226 denotes an evaporation source containing To, which is an object to be evaporated 226. For example, the object to be evaporated 226 is heated by applying an electron beam to evaporate Te. Chamber 2 under reduced pressure
Q2 is introduced into 05 from the gas introduction pipe 206. The evaporated Te combines with 02 in the chamber 20a to form a Too (0<x<2) thin film on the rotating substrate 208.

The evaporation rate is determined by the crystal oscillator method as in Example 1, and a film thickness signal of the thin film on the substrate 208 is obtained from the quartz crystal sensor evaporation rate controller 212. Further, the reflectance and transmittance, which vary from moment to moment, are measured by the reflectance measuring device 214 and the transmittance measuring device 217, and a reflectance signal and a transmittance signal are obtained as in the first embodiment. Then, the above three signals at the same point in time during thin film formation are input to the calculation circuit 219, and the refractive index n and extinction coefficient k of the thin film are input.
is calculated, and the refractive index n of the thin film is determined as a preset reference.

Or the extinction coefficient k. The comparator 228 starts the comparison with the . If the calculated n is the preset n.

or if the calculated k is larger than a preset value of 0, the gas pressure controller 227 feedback-controls the O2 flow control valve 221 to increase the O2 gas pressure in the chamber, and the composition of the thin film is changed. Too2
The composition is shifted to the rich side to bring it closer to the reference composition. On the other hand, n is n. or k is less than k. If it is smaller than 02, the 02 flow rate control valve 221 is controlled to reduce the 02 gas pressure, and the To rich Ip composition is shifted to bring it closer to the reference composition.

In the example, a TeOx thin film was explained, but T
The present invention can also be applied to the case of producing a thin film containing a specific element in OOX by using a sputtering target or evaporation source in which Te contains a specific element. In addition, the sputter target or evaporation source should be made with a T lower than the
Even if it is composed of eox, the composition can be controlled in the same way.

Furthermore, the material for forming a thin film that can be applied to the present invention is not limited to Te, nor is the gas limited to O2. It can also be effectively applied to the composition control of the formed thin film in the rating method and the like.

Effects of the Invention As described above, according to the present invention, in forming a thin film, the thickness of the thin film formed on the substrate and the combined reflectance and transmittance of the thin film and the substrate are measured in-process. After calculating the refractive index n and extinction coefficient k of the thin film from the measurement signal, the calculated value n.

A refractive index of 5° and an extinction coefficient k in which at least one of k is preset. By controlling the thin film forming conditions so as to approximate the above, in-process composition control can be realized and a desired thin film composition can be obtained, and its industrial value is extremely high.

[Brief explanation of the drawing]

1 and 2 are block diagrams of an apparatus for explaining an embodiment of the thin film forming method of the present invention, and FIG. 3 is a block diagram of an apparatus for explaining a conventional thin film forming method. 108.208.308...Substrate, 114.2
14...Reflectance measuring device, 117,217...
...Transmittance measuring device, 111.211.311...
...Crystal camera board, 106, 205, 305...
...Chamber, 119,219... Arithmetic circuit,
120...Partial pressure controller, 227...
...Gas pressure controller, 102,302-...
- Sputter target, 226... Evaporation source.

Claims (9)

[Claims] (1) When forming a thin film on a substrate, the thickness of the thin film formed on the substrate and the combined reflectance and transmittance of the thin film and substrate are measured in-process, and these three types of measurement signals are used to determine the thickness of the thin film. A refractive index n and an extinction coefficient k are calculated, and at least one of the calculated values n and k is set as a refractive index n_
0, a thin film forming method in which thin film forming conditions are controlled so as to approach an extinction coefficient k_0. (2) The preset refractive index n_0 and extinction coefficient k_0 are:
The thin film forming method according to claim 1, wherein the value is obtained by a thin film having a reference composition. (3) The thin film forming method according to claim 1, wherein the thickness of the thin film formed on the substrate is measured by a crystal oscillator method. (4) A thin film is formed on a substrate by a sputtering method, and the thin film forming conditions are controlled by the partial pressure ratio of an inert gas and a reactive gas in a chamber in a reduced pressure state. Thin film formation method. (5) A method for forming a thin film according to claim 1, in which a thin film is formed on a substrate by a vacuum evaporation method, and the thin film forming conditions are controlled by the gas pressure of a reactive gas in a chamber in a reduced pressure state. . (6) Using a sputtering target mainly composed of Te or TeO_x (0<x<2), Ar is an inert gas.
5. The thin film forming method according to claim 4, wherein the composition of the formed thin film mainly composed of TeO_x (0<x<2) is controlled by the partial pressure ratio of O_2 as a reactive gas. (7) Composition of a thin film mainly composed of TeO_x (0<x<2) formed by using an evaporation source mainly composed of Te or TeO_x (0<x<2) and the gas pressure of O_2, which is a reactive gas A method for forming a thin film according to claim 5, wherein the method controls: (8) The calculated refractive index n of the thin film is the preset refractive index n
If larger than _0, the partial pressure ratio of O_2 or O_
8. The method of forming a thin film according to claim 6, wherein the composition of the thin film is controlled by increasing the gas pressure of O_2 and, if it is low, lowering the partial pressure ratio of O_2 or the gas pressure of O_2. (9) If the calculated extinction coefficient k of the thin film is larger than the preset extinction coefficient k_0, increase the partial pressure ratio of O_2 or the gas pressure of O_2, and if it is smaller, increase the partial pressure ratio of O_2 or the gas pressure of O_2. 8. The thin film forming method according to claim 6 or 7, wherein the composition of the thin film is controlled by lowering the pressure.