JPS6219511B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention does not alter or deteriorate the low melting point glass that seals the light transmitting window member and the coating film coated on the light transmitting window member.
The present invention also relates to a chemical polishing liquid suitable for use in a light-transmitting window cap sealed with low-melting glass, which can be stably subjected to chemical polishing treatment. 2. Description of the Related Art Semiconductor devices used in digital audio disks and the like include a laser element or the like fixed on a metal outer ring and hermetically sealed with a light-transmitting window cap. This light transmitting window cap 10 has a first
As shown in the figure, Fe-Ni alloy or Fe
-Cap member 12 made of Ni-Co alloy
Furthermore, a light transmitting window 16 made of hard glass or the like is sealed with a low melting point glass 18 covering a through hole 14 provided in the center of the cap member 12. By the way, since the hard glass used as the light transmission window 16 has a softening point of about 700°C,
The low melting point glass 18 that seals this is a lead-based glass with a sealing temperature of about 500°C to prevent the light transmission window 16 from softening and deforming due to the heat during sealing and impairing its smoothness. used. On the other hand, the light-transmitting window cap 10 in which the light-transmitting window 16 is sealed with the low-melting point glass 18 as described above improves the sealing performance with the metal outer ring to which a semiconductor element or the like is fixed. In order to improve the airtightness, plating is finally performed, but in order to seal the light transmitting window 16 using the low melting point glass 18, a material such as Fe-Ni-Co alloy is used in advance. A metal oxide film is applied to the surface of the cap member 12 to improve the airtightness between the low melting point glass 18 and the cap member 12. On the other hand, before plating, in order to remove this metal oxide film that becomes an obstacle during plating, and to obtain a plating film with good adhesion, a chemical process is carried out to create a glossy and smooth metal surface. Polishing treatment is required. The present invention relates to a polishing liquid used in this chemical polishing treatment. Conventional chemical polishing solutions for Fe--Ni alloys or Fe--Ni--Co alloys include those based on nitric acid containing chlorine ions and those based on hydrogen peroxide containing fluoride. However, when the above chemical polishing liquid is used for the chemical polishing treatment of the light transmitting window cap 10,
In the case of nitric acid-based polishing solutions, NO ₃ ^- in the polishing solution,
Each of the Cl ^- and CH ₃ COO ^- ions causes a chemical reaction with lead in the low melting point glass component, resulting in low melting point glass 1.
The problem is that it alters and deteriorates 8. In addition, in the case of hydrogen peroxide, the fluoride mixed in may alter the non-opposing coating film (MgF ₂ film) applied on the light transmission window 16. Similarly to the above, there is a problem in that the low melting point glass 18 is altered or deteriorated, or the surface of the light transmitting window 16 itself is eroded and the smoothness is impaired. Therefore, in the past, when using the above-mentioned polishing liquid for a cap with a light-transmitting window, it was necessary to adjust the processing temperature, processing time, etc., but this was not only inferior in workability, but also The above disadvantages are unavoidable, resulting in poor airtightness and deterioration of the characteristics of the semiconductor device. In view of the above-mentioned difficulties, the inventor conducted extensive research and came to the conclusion that all conventional products are contaminated with halogen ions, and that these halogen ions are the root cause of excessive erosion of glass. The present invention does not incorporate such corrosive halogen ions, does not alter or deteriorate low melting point glass or coating films, and can stably perform chemical polishing treatment with good workability. The purpose is to provide a chemical polishing liquid suitable for use in caps with light transmission windows sealed with melting point glass, and its characteristics include one of citric acid, malonic acid, and succinic acid, It contains hydrogen oxide water, sulfuric acid, and a surfactant. Citric acid is preferably used as the acid. Other materials that are mildly corrosive to metals, such as malonic acid and succinic acid, are good. Concentration is 15g/~25
It is effective in the g/ range and exhibits a gentle abrasive action. Hydrogen peroxide is easily decomposed, but by using an appropriate surfactant, such as an ethylene oxide surfactant such as polyoxyethylene alkyl amine or polyoxyethylene alkyl ether, hydrogen peroxide can be decomposed easily. It acts as a negative catalyst for the decomposition of water, and in particular raises the temperature conditions under which hydrogen peroxide decomposes, making it possible to use it stably at high temperatures and increasing the polishing speed. The concentration of hydrogen peroxide solution is preferably in the range of 150ml/~250ml/, and the surfactant is 0.05g/~0.1
It is effective in small amounts of g/. Sulfuric acid is extremely less corrosive to glass than mineral acids such as nitric acid and hydrochloric acid, and remains unchanged even at high temperatures. Therefore, it stably exhibits a gentle polishing action on the above-mentioned metals at high temperatures. In terms of concentration, 40ml/~60ml/ is suitable. (1) Table 1 shows examples at various concentration settings.

【table】

[Table] No deterioration of the coating film applied to the hard glass was observed. In this way, the above-mentioned composition range is necessary to obtain a glossy surface that serves as a good plating base for Fe-Ni alloys and Fe-Ni-Co alloys, and in this composition range, there is no alteration or deterioration of low melting point glass. . (2) Next, Figure 2 shows the relationship between processing time and polishing amount. The composition was as follows. Citric acid 20g / Hydrogen peroxide 20ml / Sulfuric acid 50ml / Surfactant 0.05g / Treatment start temperature 57℃ Sample material A Fe―Ni―Co 54%―29%―17% Sample material B Fe―Ni 58%― 42% The amount of polishing required to provide the above-mentioned plating with good adhesion on the cap member 12 is 10 μm to 20 μm.
Since the diameter is about .mu.m, as is clear from FIG. 2, at a processing temperature of 57.degree. C., a short processing time of about 10 seconds is sufficient. (3) Examined using sample material A under the conditions of (2),
Table 2 shows the relationship between polishing liquid amount (ml)/treated metal surface area (cm ² ) and metal surface condition.

【table】

[Table] If the amount of polishing liquid is small relative to the surface area of the metal to be treated, the temperature of the polishing liquid will rise due to the heat of reaction.
It is desirable to use a sufficient amount of polishing liquid to avoid roughness or discoloration on the metal surface, and decomposition of the hydrogen peroxide solution in the polishing liquid itself. As described above, the chemical polishing liquid according to the present invention alters the quality of the low melting point glass that seals the light transmission window.
Metal surfaces can be coated in a short time to obtain good plating without deteriorating or deteriorating the coating film applied to the light transmitting window surface or the surface of the light transmitting window itself. It is effective in that it can be obtained. Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing a cap with a window for light transmission;
FIG. 2 is a graph showing the relationship between treatment time and polishing amount when treated with the polishing liquid according to the present invention. DESCRIPTION OF SYMBOLS 1... Cap with window for light transmission, 12... Cap member, 14... Through hole, 16... Window for light transmission, 18... Low melting point glass.

Claims (1)

[Claims] 1. A chemical polishing liquid containing one type of acid selected from citric acid, malonic acid, and succinic acid, hydrogen peroxide, sulfuric acid, and a surfactant.