Patent Application
20110120626
1. Field of the Invention
The present invention relates generally to producing bulk metal substrates which is suitable for mass production and with good flatness and ultra fine surface finishing to the roughness of less than nanometer in scale.
2. Description of the Related Art
Bulk metal substrate with ultra-fine surface finishing to the range of nanometer even sub-nanometer is needed in many applications such as hard disc, optical lens, reflectors, mirrors and new generation of magnetic capacitors. The traditional way of producing metal substrates with nanometer scaled surface finishing requires long and expensive manufacturing processes such as a CMP (chemical mechanical polishing) or direct diamond surface cutting. These machining methods will require expensive capital investment as well as long processing time. To massively producing ultra fine finishing substrates, an in-expensive method with low production cycle time is disclosed in this invention.
It is, therefore, the objectives of the present invention to provide a novel method to produce a nanometer/sub-nanometer scaled roughness bulk substrates.
Another objective of the present invention is to provide a method to produce electrically conductive metal substrate with ultra fine surface finishing.
Another objective of the present invention is to provide a method to reduce the process time needed to manufacture aforementioned substrates.
Another objective of the present invention is to provide a method to produce ultra fine surface finishing bulk substrates composing of different materials such as aluminum, copper, Nicole, iron, silver, platinum, molybdenum, metal alloy and metal composite materials.
Another objective of the present invention is to provide a method of producing substrate with ultra-fine patterned surface features without a need of using expensive photolithographic process.
To achieve above objects, the present invention provides a novel method of producing nanometer grade surface finishing substrates comprises the following steps of: producing a mother substrate which has ultra fine finished surface; a sacrificial layer being employed on the top of this surface and being used to facilitate the depletion of finished product with this mother substrate; after finishing the sacrificial layer, a vacuum tool being used to deposit a thin layer of material on the top of sacrificial layer, wherein this thin layer will be remained as a surface of a finished product. To further increase a thickness of the thin layer for ease of substrate handling and following manufacturing, the same vacuum tool or an electroplating method may be employed. After reaching a predetermined thickness suitable for continuing manufacturing, the fine surface finishing layer will be bonded with a bulk substrate; bonding of these two objects being done by vacuum bonding with elevated temperature and pressure; and therefore, a fixture is used.
These and other features, aspects, arrangements and advantages of the present invention will be understood better with regard to the following description, appended claims and accompanying drawings where:
a)-1(f) are schematic production flow charts which exhibit layer structure as well as sequence of this invention.
The present invention will be described and explained in details with reference to its embodiments. Examples of the embodiments are illustrated in the accompanying diagrams. The diagram and flow chart is drawn for the ease of understanding and explanation of present invention only; the extensions of the drawing with respect to number, ratio, position, relationship, dimension of the parts to form the embodiment will be explained or will be within the skill of the art after the following description has been read and understood.
a)-1(f) shows the diagram of the production flow of the present invention. To start production of the present embodiment, a mother substrate (100) with very fine surface finishing is needed. If a patterned surface will be produced, a negative surface should be generated on the mother substrate in order to create the needed positive patterned surface. Since this mother substrate needs to be reusable, it is preferred that these substrates should be made of hard materials which possesses high abrasive resistance and withstands high processing temperature and pressure. Materials such as quartz, ceramics and high melting temperature metal alloy can be used as raw materials for mother substrates. Also, depending on the dimension of the products needed to be produced, a mechanical strengthening mechanism can be used on the reverse side of the mother substrate in order to increase the strength of the mother substrates and to survive in the cyclic production procedure.
After finish the preparation of mother substrates, a thin polymer (110) layer is applied on the surface of the mother substrate. This polymer layer served two important functions in the present invention. First function is to be used as a sacrificial layer for ease of depletion of final product with mother substrate after production finished. The second function is to be patterned by the conventional photolithographic method in case a very complicate surface is required in which the final surface features can not be finished with single pre-patterning on mother substrate. If such a photo patterning is required, a photosensitive polymer with high surface finishing quality can be used to serve this sacrificial application.
After applying this thin sacrificial layer, a vacuum deposition process such as evaporation, sputtering or ion beam deposition will be employed to deposit the surface layer (120) which will serve as surface layer of the final products. Owing to long history of development, every possible metallic material can be deposited. Furthermore, a conventional surface defects such as nodules and voids frequently encountered in the bulk substrates can be eliminated through this vacuum process by well management of processing in adequate temperature or process range. These types of defects are usually encountered in the conventional metal substrates which cannot be resolved by any machining methods since these defects can be embedded in the bulk materials. Usually and surely, after surface cutting or polishing, these embedded defects may be unearthed. This results in very low yield rate of the metallic substrates. Therefore, traditionally, to achieve nanometer surface finishing, manufacturers have to deposit a layer of foreign material with significant thickness on these metal substrates before polishing so the embedded defected will not be unearthed during polishing. Nevertheless, typical raw metallic substrates are very rough. A pre-polishing before deposition of foreign material is needed to ensure a full coverage of the foreign materials on the bulk metal substrates. Therefore, it is a long and expensive production to achieve a fine surface finishing metallic substrates because double polishing processes cannot be avoid in the traditional production method.
After vacuum deposition, to save cost and speed up layer thickness, an electroplating (130) can be applied to increase the thickness of vacuum deposited film. There is no need to use the same materials for layers 120 and 130 even for bulk substrate (140). Therefore, a composite which preserve superior electrical and mechanical property can be designed in this production method. To reach final bulk product, the electroplating is again very expensive and time-consuming. Therefore, a bulk substrate (140) is employed to be bonded by vacuum bonding method via applying proper heat and pressure in the high vacuum environment. To facilitate vacuum bonding, a pressurized fixture (150) may be used to clamp the combined layers as showed in
Thus, the present invention comprises the steps of: producing a mother substrate (100) which has ultra fine surface finishing; a sacrificial layer (110) being employed on a top of this mother substrate to facilitate the depletion of finished product with this mother substrate; after finishing the sacrificial layer, a vacuum tool being used to deposit a thin layer (120) on the top of sacrificial layer, wherein this sacrificial layer is remained as a surface of a finished product, to increase a thickness of the thin layer (120), the same vacuum tool or an electroplating method can be employed; after reaching a predetermined thickness, an available bulk substrate (140) being employed to be bonded with these deposited fine surface layers (120 & 130); bonding of these two objects being done by vacuum bonding at elevated temperature and pressure; and therefore, a fixture (150) is used.
The present invention has been described with particular reference to certain preferred embodiments. It should be understood that the foregoing description and examples are only illustrative of the present invention. Various alternatives and modifications thereof can be devised by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the appended claims.
