JP4374689B2 - Shadow mask offset setting method and design system - Google Patents

Description

【００２３】
以上の結果より、設計透過率に対する誤差の絶対値をＴ（ｘ）とすると、オフセット量を減らす方向に変動した場合、数２のようになる。
【００２４】
【数２】

【００２５】
同様に、オフセット量を増やす方向に変動した場合、
Ｔ（ｘ）＝｜Ｆ（ｘ）−Ｆ（ｘ＋Δｘ）｜＞｜Ｆ（ｘ₀）−Ｆ（ｘ₀＋Δｘ）
｜＝Ｔ（ｘ₀）となる。
従って、最適オフセット量ｘ₀は、透過率がオフセット量の変動量Δｘの影響を最も受けにくい値である。
【００２６】
以上の果から、本発明の方法でオフセット量を設定してやれば、シャドウマスクの製造工程のマスクパターンの位置ズレ（オフセット変動量Δｘ）が発生しても透過率変化は最小限に抑えられることになる。
通常、マスクパターンの位置ズレはｘ、ｙ方向とは限らずあらゆる方向に発生する。そこで、前述の数式を２次元に一般化、厳密化して、オフセット方向と変動量Δｘの関係をを求めることができる。すなわち、小孔開口マスク２５中心を原点とするｘｙ平面上で、大孔開口マスク２６ａを任意にズラした開口マスクについて透過率Ｆ（ｘ,ｙ）を求め、その全微分ｄＦ（ｘ,ｙ）の絶対値が最小となるｘｃ、ｙｃが存在する。そのｘｃ、ｙｃが最もマスクパターンの位置ズレ（オフセット変動量Δｘ）の影響を受け難いオフセット量となる。
【００２７】
一般に、開口マスクの孔径や孔形状及び透過率を測定する斜光角度は開口マスク領域の位置によって異なる。よって、上記で求められるｘ₀またはｘｃ、ｙｃも異なるので、開口マスク領域のそれぞれの部位でｘ₀またはｘｃ、ｙｃを算出し、最適オフセット量とする。
【００２８】
最適オフセット量の設定は、前記シャドウマスクの製造方法と同一条件で、小孔パターン３１ａ及び大孔パターン３２ａを有する露光マスク３１及び露光マスク３２を用いて、金属基材２１に図６（ａ）、（ｂ）に示すような小孔開口部１１及び大孔開口部１２を作製し、３次元形状測定手段によって小孔開口部１１及び大孔開口部１２の孔形状を数値化し、オフセット量を変更しながら小孔開口部１１及び大孔開口部１２を幾何学的に組み合わせて開口マスクを予測し、その開口マスクの斜光角度についてオフセット量と透過率の関係を求め、オフセット量による微分値の絶対値が最小となるオフセット量を最適オフセット量とする。
【００２９】
さらに、決定したオフセット量での透過率が、設定値より大きければ小孔開口マスクまたは大孔開口マスクの径を大きくし、設計値より小さければ小孔開口マスクまたは大孔開口マスクの径を小さくし、透過率が規定範囲になるまで、オフセット量を絞り込むことにより、オフセット量の最適化をすることができる。
【００３０】
これは、オフセット量と透過率の関係を、幾何学的に算出する手段を提供するものである。小孔開口部１１及び大孔開口部１２の孔形状は、図６（ａ）、（ｂ）の様に半球に近い形状になる。図３の（ａ）〜（ｃ）の様に、オフセット量を変えた場合の開口マスクの形状は、小孔開口部１１及び大孔開口部１２の幾何学的組み合わせによって近似することが出来る。透過率も遮光角度とこの開口マスクの形状から求められ、オフセット量と透過率の関係が得られる。つまり、様々なオフセット量の開口マスクを作製して透過率を測定しなくても、小孔開口部１１及び大孔開口部１２の幾何学的組み合わせによってオフセット量と透過率の関係が得られる。
【００３１】
しかしながら、図１（ａ）のようにオフセット量によって透過率は変動するので、前述の微分値が最小となるときの透過率が所望の値になるとは限らない。この場合は、仮定した小孔側もしくは大孔側のエッチング形状が適切でなかったものとし、小孔側もしくは大孔側の開口部形状を変更して開口径を調整する。開口部形状の変更とは、前述の小孔開口部１１及び大孔開口部１２の製造方法において、小孔パターン３１ａ及び大孔パターン３２ａのパターン径を変更することにより開口部形状を変更する。さらに、開口部形状を変更することにより、先に求めたオフセット量対透過率の関係が成り立たないことから、改めて同関係を求め直す必要がある。これを反復して最適オフセット量を求める理由である。
【００３２】
また、前述の小孔開口部及び大孔開口部を幾何学的に組み合わせて開口マスク形状を算出することに関して、前記シャドウマスクの製造方法の図５（ａ）〜（ｆ）で説明したように、大孔開口マスク２６ａは、図５（ｄ）に示すように、小孔開口マスク２５及び大孔開口マスク２６を形成した後小孔開口マスク２５側にエッチング防止層２７を形成して大孔開口マスク２６を２次エッチングして形成するため、厳密には、大孔開口マスク２６ａの形状はエッチング防止層２７の影響を受ける。よって、単純に小孔開口部及び大孔開口部を組み合わせるのではなく、小孔開口部の形状に基づいて大孔側開口部を膨張変形する処理を含む。
【００３３】
さらに、本発明のオフセット量の設計システムは、図９に示すように、小孔開口部及び大孔開口部の３次元形状測定値を保有する手段２０１と、小孔パターン径及び大孔パターン径を入力してそれに相当する小孔開口部及び大孔開口部の孔形状を取り出す手段２０２と、オフセット量ｘに対する透過率Ｆとの関係式Ｆ（ｘ）を求める手段２０３と、オフセット量ｘに対する透過率変化率の絶対値が最小となるオフセット量ｘ₀を求める手段２０４と、透過率Ｆ（ｘ₀）が仕様値を満たしているかどうかを判断する手段２０５と、露光マスクの設計値として、小孔パターン径、大孔パターン径及びオフセット量を決定する手段２０６とを有するものである。
【００３４】
具体的には、まず、手段２０１にて、各種パターン径の小孔開口部及び大孔開口部の孔形状測定データをコンピュータに蓄積し、３次元形状測定値ＤＢ（データベース）を作成する。
【００３５】
次に、手段２０２にて、シャドウマスクの仕様に基づいた開口マスクのパターン径を入力し、３次元形状測定値ＤＢより孔形状データを引き出し、３次元ＣＡＤにて小孔開口部及び大孔開口部形状を作成する。
【００３６】
次に、手段２０３にて、オフセット量ｘを変化させて、そのオフセット量ｘに対して先の小孔開口部及び大孔開口部を組み合わせて開口マスク形状を作成し、所定の斜光角度での透過率Ｆを計算し、この動作を所定回数繰り返して関係式Ｆ（ｘ）を求める。
【００３７】
手段２０４にて、オフセット量ｘに対する透過率変化率が最小となるオフセット量ｘ₀と透過率Ｆ（ｘ₀）を求める。
【００３８】
次に、手段２０５にて、手段２０４にて求めた透過率Ｆ（ｘ₀）がシャドウマスク仕様の規定値に入っているかどうかを検定して、規定値に入っていなければ手段２０２に戻り、手段２０２以降を繰り返す。規定値に入っていれば、手段２０６にて、露光マスクの設計値として、小孔パターン径、大孔パターン径及び最適オフセット量を決定する。
【００３９】
【実施例】
以下実施例により本発明を詳細に説明する。
まず、板厚０．１３ｍｍのＦｅ−Ｎｉを主成分とする長尺帯状の合金材（アンバー材）からなる金属基材２１にカゼインと重クロム酸アンモニウムからなる水溶性感光液を塗布・乾燥して感光層２２を形成した。
【００４０】
次に、図７に示すようなシャドウマスク１００の開口マスク領域１０１の測定位置１１１〜１１７に対応した小孔パターン３１ａ及び大孔パターン３２ａを用いて、露光、現像、エッチング等のシャドウマスク作製条件と同一条件で一連のパターニング処理を行い、金属基材２１に図６（ａ）及び（ｂ）に示すような小孔開口部１１及び大孔開口部１２をそれぞれ作製した。
【００４１】
次に、上記小孔開口部１１及び大孔開口部１２の孔形状をレーザー顕微鏡、ＣＣＤ顕微鏡等の３次元形状測定装置で計測し、孔形状データを３次元ＣＡＤに取り込み、保存した。
【００４２】
次に、手段２０２及び２０３にて、上記各測定位置での小孔開口部と大孔開口部を組み合わせて作成した開口マスクに対して、それぞれの測定位置で規定された斜光角度でのオフセット量に対する透過率を算出した。その１例として、斜光角度３４度の開口マスクのオフセット量対透過率の関係を求めたものを図８に示す。手段２０４にて、オフセット量約２５μｍで透過率の変化率が０となった。しかし、その時の透過率が約１７．２５％であり、手段２０５にて、この測定位置のシャドウマスク仕様の透過率規定値１７．５％に満たない結果になった。そこで、手段２０２に戻って、小孔パターンが１％大きいものを指定して、手段２０３及び手段２０４にて、改めて開口マスクを作成し直し、透過率を求めた結果透過率は１７．５８％となり、シャドウマスク仕様の透過率規定値１７．５％を満たすことが判明し、設定測定位置での開口マスクの小孔パターン径、大孔パターン径及び最適オフセット量の設定ができた。同様にして、全ての測定位置での開口マスクの小孔パターン径、大孔パターン径及び最適オフセット量を求めた。
【００４３】
設定測定位置以外の開口マスクについては、従来通りシャドウマスク中心から開口マスクまでの距離Ｒを媒介変数とするスプライン補間で、各位置での開口マスクの小孔パターン径、大孔パターン径及び最適オフセット量を設定した。
【００４４】
次に、上記本発明のオフセット量設計システムで決定した小孔パターン径、大孔パターン径及びオフセット量の設計値を用いて露光マスク３１及び露光マスク３２を作製し、感光層２２を形成した金属基材２１の両面にセットし、位置合せ、密着露光してパターン潜像を形成し、現像処理して小孔開口パターン２３及び大孔開口パターン２４を有するレジストパターン２２ａ及びレジストパターン２２ｂを形成した。
【００４５】
次に、一次エッチング、エッチング防止層の形成、二次エッチング、剥膜処理等の一連のパターニング処理を行いシャドウマスクを作製し、シート状に断裁して、図４に示す開口マスク領域１０１及びスカート成形エリア１０２を有するフラット型シャドウマスク１００を得た。
【００４６】
【発明の効果】
本発明の方法によれば、各開口マスクに対して最適のオフセット量が設定でき、シャドウマスク製造工程での小孔開口マスクと大孔開口マスクの位置ズレによる不良が減少する。
また、小孔開口部及び大孔開口部の孔形状を３次元で数値化しＤＢ（データベース）化しているため、実際にシャドウマスクを製造する前の設計段階で、開口マスクの透過率が予測でき、オフセット量に対する透過率の関係も得られるため、マスクパターンの設計効率が上がり、高品質のシャドウマスクを得ることができる。
【図面の簡単な説明】
【図１】（ａ）は、開口マスクのオフセット量対透過率の関係式Ｆ（ｘ）を示す説明図である。
（ｂ）は、開口マスクのオフセット量対透過率変化率の関係式Ｆ'（ｘ）を示す説明図である。
【図２】（ａ）は、オフセット量０の状態を示す開口マスクの模式断面図である。
（ｂ）は、オフセット量Ｘａの状態を示す開口マスク断面図である。
【図３】（ａ）は、オフセット量０の状態を示す開口マスクの模式断面図である。
（ｂ）は、オフセット量Ｘ₁の状態を示す開口マスクの模式断面図である。
（ｃ）は、オフセット量Ｘ₂の状態を示す開口マスクの模式断面図である。
【図４】シャドウマスクの一実施例を示す平面図である。
【図５】（ａ）〜（ｆ）はシャドウマスクの製造工程の一実施例を工程順に示す説明図である。
【図６】（ａ）は、小孔パターンを用いて金属基材にフォトエッチングで形成した小孔開口部を示す模式断面図である。
（ｂ）は、大孔パターンを用いて金属基材にフォトエッチングで形成した大孔開口部を示す模式断面図である。
【図７】オフセット量を設定するための開口マスクの測定位置を示す平面図である。
【図８】オフセット量対透過率の関係の一実施例を示す説明図である。
【図９】本発明のオフセット量設計システムの一実施例を示す説明図である。
【符号の説明】
１１……小孔開口部
１２……大孔開口部
２１……金属基材
２２……感光層
２２ａ、２２ｂ……レジストパターン
２３……小孔開口パターン
２４……大孔開口パターン
２５……小孔開口マスク
２６、２６ａ……大孔開口マスク
２７……エッチング防止層
３１、３２……露光マスク
３１ａ……小孔パターン
３２ａ……大孔パターン
１００……シャドウマスク
１０１……開口マスク領域
１０２……スカート成形エリア
１１１、１１２、１１３、１１４、１１５、１１６、１１７……オフセット量を設定するための開口マスクの測定位置
２０１……小孔開口部及び大孔開口部の３次元形状測定値を保有する手段
２０２……小孔パターン径及び大孔パターン径を入力してそれに相当する小孔開口部及び大孔開口部の孔形状を取り出す手段
２０３……オフセット量ｘに対する透過率Ｆとの関係式Ｆ（ｘ）を求める手段
２０４……オフセット量ｘに対する透過率変化率の絶対値が最小となるオフセット量ｘ₀を求める手段
２０５……透過率Ｆ（ｘ₀）が仕様値を満たしているかどうかを判断する手段
２０６……露光マスクの設計値として、小孔パターン径、大孔パターン径及びオフセット量を決定する手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a setting method and a design system for setting an offset amount of a large hole pattern with respect to a small hole pattern of an exposure mask in a process of manufacturing a shadow mask by a photoetching method.
[0002]
[Prior art]
A typical color display tube is composed of an electron gun, a shadow mask, and three-color dot phosphor screens of red, green, and blue. The shadow mask is a thin iron-based material attached in front of the phosphor screen, and a large number of aperture masks through which electron beams pass are regularly arranged. One aperture mask corresponds to a set of three phosphor dots of red, green and blue, and serves to guide the three electron beams emitted from the electron gun to the respective phosphor dots.
[0003]
The shadow mask is manufactured by a process as shown in FIG.
First, after degreasing, leveling and cleaning both surfaces of a metal substrate 21 made of a low carbon steel plate having a thickness of 0.13 mm, a water-soluble photosensitive solution composed of casein, polyvinyl alcohol and ammonium dichromate is applied to both surfaces. Drying forms the photosensitive layer 22. Next, the exposure mask 31 having the small hole pattern 31a on one surface of the metal substrate 21 on which the photosensitive layer 22 is formed and the exposure mask 32 having the large hole pattern 32a on the other surface are in close contact with each other. And exposing from both sides (see FIG. 5A).
[0004]
Next, development and hardening processing are performed with a predetermined chemical solution to form a resist pattern 22a and a resist pattern 22b having a small hole opening pattern 23 and a large hole opening pattern 24 on both surfaces of the metal substrate 21 (FIG. 5B). )reference).
[0005]
Next, primary etching (spray etching) is performed from both surfaces of the metal substrate 21 on which the resist pattern 22a and the resist pattern 22b are formed using a ferric chloride solution or the like, and a predetermined shape is formed on both surfaces of the metal substrate 21. A small hole opening mask 25 and a large hole opening mask 26 are formed (see FIG. 5C).
[0006]
Next, a predetermined resin solution is formed on the metal substrate 21 on the small hole opening mask 25 side by a method such as roller coating, gravure coating, spray coating, etc., and dried and cured to form the etching prevention layer 27. (See FIG. 5 (d)).
[0007]
Next, secondary etching (spray etching) is performed until the metal substrate 21 penetrates the large hole opening mask 26 on the other surface of the metal substrate 21 using a ferric chloride solution or the like, and the large hole opening mask 26a. (See FIG. 5E).
[0008]
Next, the etching prevention layer 27, the resist pattern 22a, and the resist pattern 22b are peeled off by immersing or spraying the metal base material 21 on which the large hole opening mask 26a is formed in a heated alkaline solution, followed by washing with water and drying. Thus, a shadow mask 100 having an opening mask composed of the small hole opening mask 25 and the large hole opening mask 26a is obtained (see FIG. 5F).
[0009]
Further, a plan view of the shadow mask 100 is shown in FIG. In the figure, an opening mask region 101 is provided with a large number of opening masks comprising the above-mentioned small hole opening mask 25 and large hole opening mask 26a, and a skirt molding area 102 shows the outer shape of the shadow mask. This is a part that is molded by a press or the like when assembled.
[0010]
The shadow mask 100 manufactured by the above method is incorporated in a color picture tube, has a certain distance from the fluorescent screen between the electron gun and the fluorescent screen, and the large aperture opening mask 26a side is the fluorescent screen. Attached facing. Here, the electron beam emitted from the electron gun passes through the aperture mask composed of the small aperture aperture mask 25 and the large aperture aperture mask 26a of the shadow mask 100, and irradiates the red, green and blue phosphor dots on the phosphor screen. And displayed as a color image.
[0011]
As described above, the shadow mask 100 serves to guide the three electron beams emitted from the electron gun to the phosphor dots of red, green, and blue on the phosphor screen. A hole shape and an opening diameter (hereinafter referred to as a hole diameter) of the opening mask composed of the hole opening mask 25 and the large hole opening mask 26a are set in advance at the pattern design stage of the exposure mask in the shadow mask manufacturing process, and are predetermined after the photoetching process. The shape and hole diameter can be obtained.
[0012]
Usually, the electron gun in the color picture tube is provided on the center line of the shadow mask 100, and in the central region of the shadow mask, the electron beam emitted from the electron gun enters the shadow mask surface almost perpendicularly. That is, the electron beam is incident on the opening mask in the opening mask region 101 of the shadow mask 100 substantially perpendicularly via the small hole opening mask 25 and the large hole opening mask 26a. However, as the distance from the center of the shadow mask increases, the electron beam gradually enters the aperture mask from an oblique direction (hereinafter, the incident angle set at that position is referred to as an oblique light angle). For this reason, a phenomenon occurs in which the electron beam incident on the opening mask at a position away from the center of the shadow mask 100 is partially cut at the edge of the large hole opening mask 26a depending on the shape of the opening mask. In order to prevent the partial cut phenomenon of the electron beam and secure a certain amount of electron beam passage, the center position of the large hole opening mask 26a is shifted by a predetermined amount with respect to the center position of the small hole opening mask 25 of the opening mask. A measure is taken, which is called an offset, and the shift amount is called an offset amount.
[0013]
The offset amount will be described below. 2A and 2B are schematic cross-sectional views of the opening mask of the shadow mask. When the center line of the small hole opening mask 25 of the opening mask is X ₁ and the center line of the large hole opening mask 26 a is X ₂ , FIG. 2A shows the sectional shape of the opening mask in the center region of the shadow mask, X ₁ and X ₂ represent the state of the opening mask with the offset amount 0 existing on the same line. FIG. 2B shows the sectional shape of the opening mask away from the center of the shadow mask by a predetermined position. with respect to the center line X ₁ of illustrates a state of the aperture mask of the offset amount Xa of the center line X ₂ is shifted Xa large pore aperture mask 26a.
Thus, in the central portion of the shadow mask, the center line X ₂ of the center line X ₁ and a large pore aperture mask 26a of the stoma aperture mask 25 match as shown in FIG. 2 (a). Furthermore, in accordance with the aperture mask leaves the shadow mask periphery direction, as shown in FIG. 2 (b), the center line X ₁ and the larger hole center line X ₂ of the aperture mask 26a of the stoma aperture mask 25 is shifted offset Xa position The electron beam is partially cut to prevent a partial cut phenomenon of the electron beam.
[0014]
The offset amount of the opening mask in each part away from the center of the shadow mask in the peripheral direction is a provisionally determined large-hole mask based on the transmittance defined in the opening mask and the thickness of the metal substrate for each part. In general, a tentatively determined value is determined from the diameter, the small hole mask diameter, and the like, and then the tentatively determined value is corrected by repeating trial manufacture and measurement.
Here, the transmittance is a ratio of light incident at an oblique light angle that passes through the shadow mask, and is a value obtained by a ratio of the projected area of the aperture mask per unit area.
[0015]
As described in the shadow mask manufacturing method, the small hole opening mask 25 and the large hole opening mask 26a of the shadow mask opening mask are the exposure mask 31 and the exposure mask 32 having the small hole pattern 31a and the large hole pattern 32a. It is obtained by forming a resist pattern on both surfaces of the metal base material 21 and performing etching. Thus, the offset amount of the small hole opening mask 25 and the large hole opening mask 26a is determined by the pattern arrangement of the exposure mask 31 having the small hole pattern 31a and the exposure mask 32 having the large hole pattern 32a.
[0016]
However, the pattern exposure process using the exposure mask in the shadow mask manufacturing process shows some variation with respect to the set offset amount. As the contents of the variation, the pattern arrangement variation of the small hole pattern 31a and the large hole pattern 32a in the manufacturing process of the exposure mask 31 and the exposure mask 32 and the alignment variation of the exposure mask 31 and the exposure mask 32 are integrated. . Thus, the variation in the set offset amount in the shadow mask manufacturing process is inevitable.
For the recent increase in size and definition of the shadow mask, the variation in the offset amount causes a problem in the shape and transmittance of the aperture mask.
[0017]
[Problems to be solved by the invention]
The present invention has been devised in view of the above problems, and an offset amount setting method and design for setting the optimum offset amount of the small hole opening mask and the large hole opening mask at each part of the opening mask of the shadow mask. The purpose is to provide a system.
[0018]
[Means for Solving the Problems]
In order to achieve the above object in the present invention, first, in claim 1, exposure and development are performed using an exposure mask having a small hole pattern and a large hole pattern on the photosensitive layer formed on both surfaces of the metal substrate. Processing is performed to form a small hole resist pattern and a large hole resist pattern, and etching is performed to produce a shadow mask having an opening mask composed of a small hole opening mask on one surface and a large hole opening mask on the other surface. In the shadow mask manufacturing method, a small hole opening and a large hole opening are respectively formed in the metal substrate by photoetching under the same conditions as the shadow mask manufacturing conditions, and the small hole opening and the large hole opening are formed. The hole shape of the hole opening is digitized by a three-dimensional shape measuring means, and the relationship between the offset amount and the transmittance is obtained for the oblique light angle at the predetermined position of the opening mask. It is obtained by the offset amount setting method characterized in that the absolute value of the transmittance change rate with respect to Tsu preparative amount to optimum offset amount smallest value.
[0019]
Further, in claim 2, the means for holding the three-dimensional shape measurement value of the hole shape of the small hole opening and the large hole opening, and the small hole corresponding to the small hole pattern diameter and the large hole pattern diameter are input. Means for creating openings and large-hole openings, means for obtaining a relational expression F (x) of the transmittance F with respect to the offset amount x, and an offset amount that minimizes the absolute value of the transmittance change rate with respect to the offset amount x means for determining x ₀ , means for determining whether or not the transmittance F (x ₀ ) satisfies a specified value of the shadow mask specification, and a pattern design value of the exposure mask as a small hole pattern diameter, a large hole pattern diameter, and An offset amount design system comprising at least means for determining an offset amount.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
In the offset amount setting method of the present invention, the small hole opening 11 and the large hole opening as shown in FIGS. 6A and 6B are formed in the metal base material 21 under the same conditions as the manufacturing conditions of the shadow mask. The portions 12 are respectively produced by photo-etching, and the hole shapes of the small hole openings 11 and the large hole openings 12 are quantified by a three-dimensional shape measuring means, and an offset amount with respect to an oblique light angle at a predetermined position of the opening mask. And the transmittance, and the value that minimizes the absolute value of the transmittance change rate for each offset amount is set as the optimum offset amount.
[0021]
In general, the relationship between the offset amount of the opening mask and the transmittance is a parabolic graph y = F (x) as shown in FIG. When this is differentiated, a monotonically decreasing graph F ′ (x) is obtained as shown in FIG. That is, the offset amount that is the vertex of the graph of FIG. 1A is X ₀ (that is, F ′ (X ₀ ) = 0), and the arbitrary offset amounts x ₁ and x ₂ satisfy x ₀ <x ₁ <x ₂ . If it ’s a relationship,
| F ′ (x ₀ ) | <| F ′ (x ₁ ) | <| F ′ (x ₂ ) |
Conversely, if x ₀ > x ₁ > x ₂ ,
| F ′ (x ₀ ) | <| F ′ (x ₁ ) | <| F ′ (x ₂ ) |
Consider a case where the design offset amount x is sufficiently different from x ₀ for the offset amount variation Δx> 0. That is, when | x ₀ −x |> Δx, since F ′ (x) is monotonous in the range [x−Δx, x + Δx], Equation 1 is obtained.
[0022]
[Expression 1]

[0023]
From the above results, assuming that the absolute value of the error with respect to the design transmittance is T (x), Equation 2 is obtained when the offset value is changed in a decreasing direction.
[0024]
[Expression 2]

[0025]
Similarly, if it fluctuates in the direction of increasing the offset amount,
T (x) = | F (x) −F (x + Δx) |> | F (x ₀ ) −F (x ₀ + Δx)
| = T (x ₀ ).
Therefore, the optimum offset amount x ₀ is a value at which the transmittance is least affected by the variation amount Δx of the offset amount.
[0026]
From the above results, if the offset amount is set by the method of the present invention, the transmittance change can be suppressed to the minimum even if the mask pattern positional deviation (offset fluctuation amount Δx) in the shadow mask manufacturing process occurs. Become.
Usually, the positional deviation of the mask pattern is not limited to the x and y directions, but occurs in all directions. Therefore, the relationship between the offset direction and the fluctuation amount Δx can be obtained by generalizing and strictening the above-described mathematical formula in two dimensions. That is, the transmittance F (x, y) is obtained for an aperture mask obtained by arbitrarily shifting the large aperture mask 26a on the xy plane with the center of the small aperture mask 25 as the origin, and the total differential dF (x, y) is obtained. There are xc and yc that minimize the absolute value of. The xc and yc are the offset amounts that are hardly affected by the positional deviation (offset fluctuation amount Δx) of the mask pattern.
[0027]
In general, the oblique angle for measuring the hole diameter, hole shape, and transmittance of the opening mask varies depending on the position of the opening mask region. Therefore, since x ₀ or xc, yc obtained above is also different, x _0, xc, yc is calculated at each part of the opening mask region and set as the optimum offset amount.
[0028]
The optimal offset amount is set on the metal substrate 21 using the exposure mask 31 and the exposure mask 32 having the small hole pattern 31a and the large hole pattern 32a under the same conditions as the shadow mask manufacturing method. The small hole opening 11 and the large hole opening 12 as shown in (b) are prepared, and the hole shapes of the small hole opening 11 and the large hole opening 12 are quantified by the three-dimensional shape measuring means, and the offset amount is set. The opening mask is predicted by geometrically combining the small hole opening 11 and the large hole opening 12 while changing, the relationship between the offset amount and the transmittance is obtained for the oblique light angle of the opening mask, and the differential value based on the offset amount is calculated. The offset amount that minimizes the absolute value is set as the optimum offset amount.
[0029]
Further, if the transmittance at the determined offset amount is larger than the set value, the diameter of the small hole opening mask or the large hole opening mask is increased, and if it is smaller than the design value, the diameter of the small hole opening mask or the large hole opening mask is decreased. Then, the offset amount can be optimized by narrowing the offset amount until the transmittance falls within the specified range.
[0030]
This provides a means for geometrically calculating the relationship between the offset amount and the transmittance. The hole shapes of the small hole opening 11 and the large hole opening 12 are close to a hemisphere as shown in FIGS. As shown in FIGS. 3A to 3C, the shape of the opening mask when the offset amount is changed can be approximated by the geometric combination of the small hole opening 11 and the large hole opening 12. The transmittance is also obtained from the light shielding angle and the shape of the opening mask, and the relationship between the offset amount and the transmittance can be obtained. That is, the relationship between the offset amount and the transmittance can be obtained by the geometric combination of the small hole opening portion 11 and the large hole opening portion 12 without preparing the aperture masks having various offset amounts and measuring the transmittance.
[0031]
However, since the transmittance varies depending on the offset amount as shown in FIG. 1A, the transmittance when the differential value is minimized is not always a desired value. In this case, it is assumed that the assumed etching shape on the small hole side or the large hole side is not appropriate, and the opening diameter is adjusted by changing the opening shape on the small hole side or the large hole side. The change of the opening shape means that the opening shape is changed by changing the pattern diameters of the small hole pattern 31a and the large hole pattern 32a in the manufacturing method of the small hole opening 11 and the large hole opening 12 described above. Furthermore, since the relationship between the offset amount and the transmittance obtained previously cannot be established by changing the shape of the opening, it is necessary to obtain the relationship again. This is the reason why the optimum offset amount is obtained by repeating this.
[0032]
Further, as described in FIGS. 5A to 5F of the shadow mask manufacturing method, the aperture mask shape is calculated by geometrically combining the small hole openings and the large hole openings described above. As shown in FIG. 5D, the large hole opening mask 26a is formed by forming an etching prevention layer 27 on the small hole opening mask 25 side after forming the small hole opening mask 25 and the large hole opening mask 26. Strictly speaking, since the opening mask 26 is formed by secondary etching, the shape of the large hole opening mask 26 a is influenced by the etching prevention layer 27. Therefore, a process of expanding and deforming the large hole side opening based on the shape of the small hole opening is included instead of simply combining the small hole opening and the large hole opening.
[0033]
Furthermore, as shown in FIG. 9, the offset amount design system according to the present invention includes means 201 for holding small hole openings and three-dimensional shape measurement values of large hole openings, small hole pattern diameters and large hole pattern diameters. , A means 202 for extracting the hole shape of the small hole opening and the large hole opening corresponding thereto, a means 203 for obtaining a relational expression F (x) of the transmittance F with respect to the offset amount x, and for the offset amount x Means 204 for obtaining an offset amount x ₀ that minimizes the absolute value of the transmittance change rate, means 205 for judging whether or not the transmittance F (x ₀ ) satisfies the specification value, and exposure mask design values: And means 206 for determining a small hole pattern diameter, a large hole pattern diameter, and an offset amount.
[0034]
Specifically, first, the means 201 accumulates small hole openings of various pattern diameters and hole shape measurement data of the large hole openings in a computer to create a three-dimensional shape measurement value DB (database).
[0035]
Next, the means 202 inputs the pattern diameter of the opening mask based on the specifications of the shadow mask, extracts the hole shape data from the three-dimensional shape measurement value DB, and extracts the small hole opening and the large hole opening by the three-dimensional CAD. Create a part shape.
[0036]
Next, in the means 203, the offset amount x is changed, and an aperture mask shape is created by combining the previous small hole opening and large hole opening with respect to the offset amount x, and at a predetermined oblique light angle. The transmittance F is calculated, and this operation is repeated a predetermined number of times to obtain the relational expression F (x).
[0037]
The means 204 obtains an offset amount x ₀ and a transmittance F (x ₀ ) that minimize the transmittance change rate with respect to the offset amount x.
[0038]
Next, the means 205 tests whether or not the transmittance F (x ₀ ) obtained by the means 204 is within the specified value of the shadow mask specification, and if not, returns to the means 202, The means 202 and subsequent steps are repeated. If it is within the specified value, the means 206 determines the small hole pattern diameter, the large hole pattern diameter, and the optimum offset amount as the design value of the exposure mask.
[0039]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
First, a water-soluble photosensitive solution composed of casein and ammonium dichromate was applied to a metal substrate 21 composed of a long strip-shaped alloy material (amber material) mainly composed of Fe-Ni having a thickness of 0.13 mm and dried. Thus, a photosensitive layer 22 was formed.
[0040]
Next, using the small hole pattern 31a and the large hole pattern 32a corresponding to the measurement positions 111 to 117 of the opening mask region 101 of the shadow mask 100 as shown in FIG. A series of patterning processes were performed under the same conditions as above, and a small hole opening 11 and a large hole opening 12 as shown in FIGS.
[0041]
Next, the hole shapes of the small hole opening 11 and the large hole opening 12 were measured with a three-dimensional shape measuring device such as a laser microscope or a CCD microscope, and the hole shape data was taken into a three-dimensional CAD and stored.
[0042]
Next, with the means 202 and 203, with respect to the opening mask created by combining the small hole opening and the large hole opening at each measurement position, the offset amount at the oblique light angle defined at each measurement position. The transmittance with respect to was calculated. As an example, FIG. 8 shows the relationship between the offset amount and the transmittance of an aperture mask having an oblique light angle of 34 degrees. With the means 204, the transmittance change rate became zero with an offset amount of about 25 μm. However, the transmittance at that time was about 17.25%, and the result of the means 205 was less than the transmittance specified value 17.5% of the shadow mask specification at this measurement position. Therefore, returning to the means 202, the one having a small hole pattern of 1% is specified, and the means 203 and 204 again create an opening mask, and the transmittance is obtained. As a result, the transmittance is 17.58%. Thus, it was found that the prescribed transmittance value of 17.5% in the shadow mask specification was satisfied, and the small hole pattern diameter, large hole pattern diameter, and optimum offset amount of the opening mask at the set measurement position could be set. Similarly, the small hole pattern diameter, large hole pattern diameter, and optimum offset amount of the opening mask at all measurement positions were obtained.
[0043]
For aperture masks other than the set measurement position, the aperture mask has small hole pattern diameters, large hole pattern diameters, and optimum offsets by spline interpolation using the distance R from the shadow mask center to the aperture mask as a parameter as before. The amount was set.
[0044]
Next, the exposure mask 31 and the exposure mask 32 are prepared using the design values of the small hole pattern diameter, the large hole pattern diameter and the offset amount determined by the offset amount design system of the present invention, and the metal on which the photosensitive layer 22 is formed. The resist pattern 22a and the resist pattern 22b having the small hole opening pattern 23 and the large hole opening pattern 24 were formed by setting the both surfaces of the base material 21, aligning, closely exposing to form a pattern latent image, and developing it. .
[0045]
Next, a shadow mask is manufactured by performing a series of patterning processes such as primary etching, formation of an etching prevention layer, secondary etching, and delamination, and the sheet is cut into a sheet shape. Then, the opening mask region 101 and the skirt shown in FIG. A flat shadow mask 100 having a molding area 102 was obtained.
[0046]
【The invention's effect】
According to the method of the present invention, an optimum offset amount can be set for each aperture mask, and defects due to misalignment between the small hole aperture mask and the large hole aperture mask in the shadow mask manufacturing process are reduced.
In addition, since the hole shapes of the small hole openings and large hole openings are numerically converted into a three-dimensional database (DB), the transmittance of the opening mask can be predicted at the design stage before actually manufacturing the shadow mask. Since the relationship of the transmittance with respect to the offset amount is also obtained, the mask pattern design efficiency is improved, and a high quality shadow mask can be obtained.
[Brief description of the drawings]
FIG. 1A is an explanatory diagram showing a relational expression F (x) between an offset amount of an opening mask and a transmittance.
(B) is explanatory drawing which shows the relational expression F '(x) of the offset amount of an opening mask versus the transmittance | permeability change rate.
FIG. 2A is a schematic cross-sectional view of an aperture mask showing a state in which an offset amount is zero.
(B) is a sectional view of the opening mask showing the state of the offset amount Xa.
FIG. 3A is a schematic cross-sectional view of an opening mask showing a state where an offset amount is zero.
(B) is a schematic cross-sectional view of the aperture mask indicating the state of the offset amount X _1.
(C) is a schematic cross-sectional view of the aperture mask indicating the state of the offset X _2.
FIG. 4 is a plan view showing an example of a shadow mask.
FIGS. 5A to 5F are explanatory views showing an example of a shadow mask manufacturing process in the order of processes; FIGS.
FIG. 6A is a schematic cross-sectional view showing a small hole opening formed in a metal substrate by photoetching using a small hole pattern.
(B) is a schematic cross-sectional view showing a large hole opening formed by photoetching on a metal substrate using a large hole pattern.
FIG. 7 is a plan view showing a measurement position of an aperture mask for setting an offset amount.
FIG. 8 is an explanatory diagram showing an example of the relationship between the offset amount and the transmittance.
FIG. 9 is an explanatory diagram showing an embodiment of an offset amount design system according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Small hole opening part 12 ... Large hole opening part 21 ... Metal substrate 22 ... Photosensitive layer 22a, 22b ... Resist pattern 23 ... Small hole opening pattern 24 ... Large hole opening pattern 25 ... Small Hole opening masks 26 and 26a... Large hole opening mask 27... Etching prevention layer 31 and 32... Exposure mask 31a... Small hole pattern 32a. ... Skirt forming areas 111, 112, 113, 114, 115, 116, 117 ... Measurement position 201 of the opening mask for setting the offset amount ... Three-dimensional shape measurement values of the small hole opening and the large hole opening Means for holding 202 ...... Means for inputting small hole pattern diameter and large hole pattern diameter and taking out the corresponding hole shape of the small hole opening and large hole opening 203. Off Tsu DOO amount relational expression F between the transmittance F against x (x) determining the unit 204 obtains the offset amount x ₀ of the absolute value of the transmittance change rate is minimized for ...... offset amount x means 205 ...... transmittance F Means 206 for determining whether or not (x ₀ ) satisfies the specification value ... Means for determining the small hole pattern diameter, large hole pattern diameter and offset amount as the design value of the exposure mask

Claims (2)

The photosensitive layer formed on both sides of the metal substrate is exposed and developed using an exposure mask having a small hole pattern and a large hole pattern, and a small hole resist pattern and a large hole resist pattern are formed and etched. In the shadow mask manufacturing method for manufacturing a shadow mask having an aperture mask composed of a small hole opening mask on one surface and a large hole opening mask on the other surface, the small holes are formed under the same conditions as the shadow mask manufacturing conditions. An opening and a large hole opening are respectively formed on the metal substrate by photoetching, and the hole shapes of the small hole opening and the large hole opening are quantified by a three-dimensional shape measuring unit, and a predetermined shape of the opening mask is determined. Obtain the relationship between the offset amount and transmittance for the oblique light angle at the position, and set the optimum offset value that minimizes the absolute value of the transmittance change rate for each offset amount. Offset amount setting method characterized by that. Means for holding three-dimensional shape measurement values of the hole shape of the small hole opening and the large hole opening, and inputting the small hole pattern diameter and the large hole pattern diameter to correspond to the small hole opening and the large hole opening shape. , A means for obtaining a relational expression F (x) of the transmittance F with respect to the offset amount x, a means for obtaining an offset amount x _{0 at} which the absolute value of the transmittance change rate with respect to the offset amount x is minimized, and transmission Means for determining whether the rate F (x ₀ ) satisfies a specified value of the shadow mask specification; means for determining a small hole pattern diameter, a large hole pattern diameter, and an offset amount as a pattern design value of an exposure mask; A system for designing an offset amount, characterized by comprising:

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