Method for forming thin films and apparatus therefor

Abstract

A vapor deposition process for depositing TiO2 and a vapor desposition process for depositing SiO2 are alternately repeated in a multi-layer film forming process. A refractive index that a thin film formed by each vapor depositing will provide is individually determined prior to each relative vapor depositing, and vapor deposition control data is prepared based on such a refractive index. Each vapor deposition is controlled by using a relative vapor deposition control data thus prepared. Therefore, each vapor deposition process can be accurately controlled according to the refractive index of a thin film even if repeated vapor deposition processes change the refractive index. Accordingly, a multilayer film having desired optical characteristics can be formed.

1 . A method for forming a thin film by vapor-deposition, comprising:
 providing a multilayer substrate and a monitor substrate in a vacuum chamber;   vapor-depositing a first material according to first deposition control data to form a first thin film;   vapor-depositing a second material according to second deposition control data to form a second thin film, the second deposition control data being independent from the first deposition control data;   alternating the vapor-deposition of the first material and the vapor-deposition of the second material to form a multilayer film on the multilayer substrate, the multilayer film including N layers of the first thin film and at least (N−1) layers of the second thin film, N being an integer more than 1;   exchanging the monitor substrate with a new monitor substrate every time a formation of an i-th single layer film of the first material on the monitor substrate by an i-th vapor-deposition of the first material is completed, i being all integers from 1 through (N−1);   measuring a refractive index of the i-th single layer film of the first material on the monitor substrate, comprising:   irradiating measuring light on the i-th single layer film on the monitor substrate to measure an amount of reflected light therefrom, the measuring light having a single wavelength; and
 normalizing the measured amount of reflected light to calculate the refractive index of the i-th single layer film of the first material; and 
   generating the first deposition control data for an (i+1)-th vapor-deposition of the first material, based on only the measured refractive index of the i-th single layer film of the first material.   
   
   
       2 . The method according to  claim 1 , wherein the first deposition control data for the (i+1)-th vapor-deposition of the first material is determined based on the measured refractive index of the i-th single layer film of the first material and a desired optical thickness of the (i+1)-th first thin film to be formed in the (i+1)-th vapor-deposition of the first material. 
   
   
       3 . The method according to  claim 2 , further comprising:
 irradiating the measuring light on the monitor substrate during the i-th vapor-deposition of the first material to measure an amount of reflected light therefrom; and   ending the i-th vapor-deposition of the first material if the measured amount of reflected light achieves a prescribed relationship with the first deposition control data for the i-th vapor-deposition of the first material.   
   
   
       4 . The method according to  claim 1 , further comprising:
 setting the measured refractive index of the i-th single layer film of the first material on the monitor substrate as the refractive index of the (i+1)-th first thin film to be formed on the second thin film in the (i+1)-th vapor-deposition of the first material; and   generating the first deposition control data for the (i+1)-th vapor-deposition of the first material, based on the regarded refractive index and a desired optical thickness of the (i+1)-th first thin film to be formed on the second thin film in the (i+1)-th vapor-deposition of the first material.   
   
   
       5 . A method for forming a thin film by vapor deposition, comprising:
 providing a preliminary substrate and a monitor substrate in a vacuum chamber;   vapor-depositing a material according to deposition control data to form a preliminary thin film;   repeating a vapor-deposition of the material to form a preliminary multilayer film on the preliminary substrate, the preliminary multilayer film having N layers of preliminary thin films, N being an integer more than 1;   exchanging the monitor substrate every time a formation of an i-th single layer film on the monitor substrate by an i-th vapor-deposition of the material, i being all integers from 1 through N:   measuring a refractive index of the i-th single layer film on the monitor substrate, comprising:
 irradiating measuring light on the i-th single layer film on the monitor substrate to measure an amount of reflected light therefrom, the measuring light having a single wavelength; and 
 normalizing the measured amount of reflected light to calculate the refractive index of the i-th single layer; 
   generating deposition control data for the i-th vapor-deposition of the material, based on the measured refractive index of the i-th single layer film;   providing a multilayer substrate in the vacuum chamber after forming the preliminary multilayer film;   repeating the vapor-deposition of the material N-times by using the i-th deposition control data in numerical order, thereby forming a multilayer film having N layers on the multilayer substrate.   
   
   
       6 . The thin film forming method according to  claim 5 , wherein the deposition control data for the i-th vapor-deposition of the material is generated based on the measured refractive index of the i-th single layer film on the preliminary substrate and a desired optical thickness of the i-th thin film to be formed on the multilayer substrate in the i-th vapor-deposition of the material. 
   
   
       7 . An apparatus for forming a thin film by vapor-deposition, comprising:
 a deploying unit for deploying a multilayer substrate and a monitor substrate;   a vapor-deposition unit for vapor-depositing a first material and a second material alternatively, the first material being vapor-deposited according to a first control data to form a first thin film, the second material being vapor-deposited according to a second control data to form a second thin film, the first control data being independent from the second control data;   a measuring unit for measuring a refractive index of a single layer film formed on the monitor substrate; and   a control unit for alternating the vapor-deposition of the first material and the vapor-deposition of the second material to form a multilayer film on the multilayer substrate, the multilayer film having N layers of the first thin film and at least (N−1) layers of the second thin film, N being an integer more than 1, wherein   the monitor substrate is exchanged every time a formation of an i-th single layer film of the first material on the monitor substrate by an i-th vapor-deposition of the first material is completed, i being all integers from 1 through (N−1);   the measuring unit irradiates measuring light on the i-th single layer film on the monitor substrate to measure an amount of reflected light therefrom, the measuring light having a single wavelength;   the control unit normalizes the measured amount of reflected light, calculates the refractive index of the i-th single layer film of the first material, and generates the first deposition control data for the (i+1)-th vapor-deposition of the first material on the second thin film, based on only the measured refractive index of the i-th single layer film of the first material.   
   
   
       8 . The apparatus according to  claim 7 , wherein the control unit generates the first deposition control data for the (i+1)-th vapor-deposition of the first material on the second thin film, based on only the determined refractive index of the i-th single layer film of the first material and a desired optical thickness of the (i+1)-th first thin film to be formed on the second film in the (i+1)-th vapor-deposition of the first material.