High Resolution Recording Medium and Method for Producing Same

This invention relates to recording mediums displaying a high resolution multicolor pattern. These recording mediums are especially used in the formation of microtopographical maps.

The recording of multicolor images is described in U.S. Pat. No. 3,727,233. The recording medium disclosed in this patent is made by applying a metal layer of high reflectivity to a glass substrate and covering this metal layer with an organic polymer layer. The desired pattern is formed on the polymer layer by exposing it to electron beams. The irradiation intensity of the electron beams determines the pattern formed by the polymerization of the layer. Over the polymer layer, another metal layer of high reflectivity is applied. The interference patterns yield a multicolor image when viewed under natural light. One disadvantage of this method is that the metal layers are of equal thickness over the entire substrate, thereby permitting no variations in the saturation of the individual colors of the image. The patterned interference layer formed by the organic polymer is very heat sensitive. Because of this and the high elimination strength associated with this, strong reenlargement (Ruckvergrosserung) of the multicolor image is not permitted. The deficient lightfastness and shrinkage of the organic polymer interference layer over time can cause the colors to change.

The German unexamined patent specification No. OS 26 58 623 discloses a recording medium which records with high information density. This recording medium is particularly used for multicolor micro-images. At least two interference filters (Interferenzfilter) for two different colors are applied onto the substrate of this recording medium. Each of the interference filters is made with an unpatterned inorganic absorption-free interference layer which extends with equal thickness over the entire substrate. This inorganic interference layer is bounded on each side by at least one inorganic reflecting layer which forms the pattern of the recording. In another embodiment disclosed in this patent specification, the unpatterned interference layer is bounded on each surface by at least one patterned, high-refracting absorption-free layer. Between every two high-refracting layers there is present an unpatterned, low-refracting absorption-free layer. The presence of the unpatterned interference layers which extend with equal thickness over the entire substrate in the different embodiments of this patent specification, incurs the requirement that for each desired color a series of patterning steps is necessary. During this process the exposure mask must be adjusted for each patterning step, requiring the greatest of precision. The adjustment of the exposure mask is also very time consuming.

The present invention is directed to a recording medium for high resolution multicolor patterns made with patterned or pattern-forming layer packs. The pattern-forming layers of the layer packs are separate from one another on the substrate. The pattern-forming layers of a layer pack are applied successively to the substrate in a sequence corresponding to a color in the multicolor pattern. The layer packs include an interference filter and/or an edge filter (Kantenfilter). In recording mediums with interference filters, at least part of the interference layer is a pattern-forming layer in a layer pack.

It is an object of the present invention to reduce the number of process steps necessary in creating the recording. Several pattern-forming layers are successively applied over the whole surface of the substrate after a layer of photoresist has been developed. The pattern is formed for all of these layers at one time when the remaining photoresist is removed with all of the layers overlying it. A further object of the present invention is avoiding the problems of adjusting the exposure mask for multiple patterning steps, thereby improving the optical quality of the recorded pattern.

Advantageously, the present invention allows for production of a recording medium with great savings in time and cost. The method used to produce the recording medium is more accurate so that the rejection rate is considerably lower than in formerly used methods. In addition, the present invention achieves a better color hue purity and color hue saturation.

The invention itself, together with further objects and attendant advantages, will best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

FIGS. 1a-c are schematic diagrams of recording mediums of the present invention having metal dielectric interference filters;

FIGS. 2a and b are schematic diagrams of recording mediums of the present invention having purely dielectric interference filters (reindielektrischen Interferenzfiltern);

FIGS. 3a and b are schematic diagrams of recording mediums of the present invention having semi-filters (Halbfiltern);

FIGS. 4a-d are schematic diagrams of recording mediums of the present invention having induced transmission filters (induzierten Transmissionsfiltern);

FIGS. 5a and b are schematic diagrams of recording mediums of the present invention having edge filters (reflectors); and

FIGS. 6a and b are schematic diagrams of recording mediums of the present invention having edge filters and metal dielectric filters.

Referring now to FIGS. 1a-c, there are shown recording mediums of the present invention using dielectric interference filters in the form of pattern-forming layer packs 1.sub.1, 1.sub.2 and 1.sub.3 to create a first color and pattern forming layers packs 2.sub.1, 2.sub.2 and 2.sub.3 to form a second color. The layer packs 1.sub.1,2.sub.1 are generated to form the recording medium of FIG. 1a as follows. A first photoresist layer (not shown) is applied to the whole surface of a substrate 3.sub.1. This layer is exposed by means of a first exposure mask. After the first photoresist layer has been developed, an inorganic reflecting layer 4.sub.1 is applied over the whole surface of the substrate 3.sub.1. This is followed by the application of an inorganic absorption free interference layer 5.sub.1 to the whole substrate surface. The optical thickness of the interference layer 5.sub.1 defines the first color. The interference layer 5.sub.1 is covered by an inorganic layer 6.sub.1 over the whole surface of the substrate. The remaining first photoresist layer is removed together with the layers 4.sub.1 -6.sub.1 overlying the remaining photoresist layer. This leaves only the layer pack 1.sub.1 on the substrate 3.sub.1.

To generate a second color on the substrate 3.sub.1, a second photoresist layer is applied over the whole surface. This is then exposed by means of a second exposure mask. After the second photoresist layer has been developed, an inorganic layer 7.sub.1, an inorganic absorption-free interference layer 8.sub.1 and an inorganic layer 9.sub.1 are applied over the whole surface of the substrate 3.sub.1. The interference layer 8.sub.1 defines the second color hue. The remaining second photoresist layer together with the layers 7.sub.1 -9.sub.1 overlying it is removed. This leaves a second layer pack 2.sub.1 locally separate and independent from the layer pack 1.sub.1 on the substrate 3.sub.1.

Another embodiment for recording mediums having dielectric interference filters of the present invention is shown in FIG. 1b. Here the first step in the process of generating the recording is to apply an inorganic reflecting layer 4.sub.2 over the whole surface of the substrate 3.sub.2. The inorganic reflecting layers are generally made of metal and are hereinafter referred to as metal layers. Then, to generate a first color hue, a first photoresist layer is applied over the surface. The first photoresist layer is exposed by means of a first exposure mask and the layer is developed. Then, over the whole surface of the substrate 3.sub.2 an inorganic absorption-free interference layer 5.sub.2 defining the first color hue is applied. Over this a metal layer 6.sub.2 is placed. The remaining first photoresist layer together with the layers 5.sub.2,6.sub.2 present on top of it is removed. This leaves the layer pack 1.sub.2 on the substrate 3.sub.2. A second photoresist layer is applied over the whole surface of the substrate. This layer is exposed by means of a second exposure mask to form the pattern for the second color. After the second photoresist layer has been developed, an inorganic absorption-free interference layer 8.sub.2 is applied over the whole surface of the substrate 3.sub.2. A metal layer 9.sub.2 is applied over the interference layer 8.sub.2. The remainder of the second photoresist layer together with the layers 8.sub.2,9.sub.2 on top of it is removed to leave the layer 8.sub.2, 9.sub.2 separate from the layers 5.sub.2, 6.sub.2 on the substrate 3.sub.2.

For still another embodiment of this recording medium reference is now made to FIG. 1c. A metal layer 4.sub.3 is applied over the entire surface of the layer carrier 3.sub.3. Over the metal layer 4.sub.3, an inorganic absorption-free interference layer 5.sub.3 for the generation of the first color is applied. This layer is subsequently covered by a first photoresist layer. The same steps as before are followed. The first photoresist layer is exposed and developed. The first layer pack 1.sub.3 is completed by applying a metal layer 6.sub.3 over the substrate 3.sub.3, followed by the removal of the first photoresist layer with the metal layer 6.sub.3 positioned over it. This leaves the layer pack 1.sub.3 on the substrate 3.sub.3. To generate the second color, a second photoresist layer is applied over the whole surface of the substrate 3.sub.3 and this is exposed by means of a second exposure mask. After the second photoresist layer has been developed, an inorganic absorption-free interference layer 8.sub.3 is applied over the whole surface of the substrate to complete the interference layer for the second layer pack. A metal layer 9.sub.3 is then applied over the whole surface. Once again, the remainder of the second photoresist layer, together with the layers 8.sub.3, 9.sub.3 present on top of it, are removed. This leaves the layers 8.sub.3, 9.sub.3 and the layer 6.sub.3 separated on the substrate 3.sub.3.

In this embodiment just described for FIG. 1c, the interference layers 5.sub.3 and 8.sub.3 combine to define the second color. The metal layer 6.sub.3 for layer pack 1.sub.3 and the interference layer 8.sub.3 and metal layer 9.sub.3 for layer pack 2.sub.3 are the pattern-forming layers in this embodiment. In FIG. 1b, the pattern-forming layers are the layers 5.sub.2,6.sub.2 in the layer pack 1.sub.2 and the layers 8.sub.2,9.sub.2 in the layer pack 2.sub.2. In FIG. 1a, the pattern-forming layers are the layers 4.sub.1,5.sub.1,6.sub.1 in layer pack 1.sub.1 and the layers 7.sub.1,8.sub.1,9.sub.1 in the layer pack 2.sub.1. The sequence of the pattern-forming layers in each of the layer packs 1, 2 correspond to the color displayed by the respective layer pack. The metal layers 4,6,7,9 are partially permeable layers.

The present invention may also be made of recording mediums having purely dielectric interference filters. Referring now to FIGS. 2a and b, layer packs 11.sub.1,11.sub.2 form the pattern for a first color and pattern-forming layer packs 12.sub.1,12.sub.2 produce a second color.

The first step in generating the recording medium of FIG. 2a is to apply over the entire surface of the substrate 13.sub.1, a first photoresist layer. The photoresist layer is exposed using a first exposure mask. After the photoresist layer has been developed, the following layers are successively applied to the entire surface of the substrate 13.sub.1 in the following sequence corresponding to the first color: a high-refracting absorption-free layer 14.sub.1, a low-refracting absorption-free layer 15.sub.1, a high-refracting absorption-free layer 16.sub.1, an inorganic absorption-free interference layer 17.sub.1 to define the first color, a high-refracting absorption-free layer 18.sub.1, a low-refracting absorption-free layer 19.sub.1 and a high-refracting absorption-free layer 20. The remaining first photoresist layer, together with the layers 14.sub.1 -20.sub.1 present over it, is then removed. This leaves the layer pack 11.sub.1 on the substrate 13.sub.1. The second color is generated in the same manner. A second photoresist layer is applied over the whole surface of the substrate 13.sub.1. This is exposed by means of a second exposure mask. After this second photoresist layer has been developed, the pattern-forming layers for the second layer pack 12.sub.1 are applied over the whole surface of the substrate. The layers as applied in succession include a high-refracting absorption-free layer 21.sub.1, a low-refracting absorption-free layer 22.sub.1, a high-refracting absorption-free layer 23.sub.1, an inorganic absorption-free interference layer 24.sub.1 defining the second color, a high-refracting absorption-free layer 25.sub.1, a low-refracting absorption-free layer 26.sub.1 and a high-refracting absorption-free layer 27.sub.1. As usual, the remainder of the second photoresist layer, together with the layers 21.sub.1 -27.sub.1 lying over it, is then removed. This leaves the layer packs 12.sub.1 and 11.sub.1 independent from one another on the substrate 13.sub.1.

Another embodiment of the present invention using the purely dielectric interference filters is shown in FIG. 2b. Over the entire surface of the substrate 13.sub.2 are applied the whole-surface layers including a high-refracting absorption-free layer 14.sub.2, a low-refracting absorption-free layer 15.sub.2 and a high-refracting absorption-free layer 16.sub.2. The substrate 13.sub.2 is then covered with the first photoresist layer for the generation of the first color. The photoresist layer is exposed and developed using a first exposure mask. This is followed by applying an inorganic absorption-free interference layer 17.sub.2 over the whole surface of the substrate 13.sub.2 to define the first color. The remaining layers are successively applied over the surface of the substrate 13.sub.2 in a sequence corresponding to the first color. In order, these layers include a high-refracting absorption-free layer 18.sub.2, a low-refracting absorption-free layer 19.sub.2 and a high-refracting absorption-free layer 20.sub.2. The remaining first photoresist layer is removed together with the layers 17.sub.2 -20.sub.2 overlying it. The layer pack 11.sub.2 is left remaining on the substrate 13.sub.2. To generate the second layer pack 12.sub.2, a second photoresist layer is applied over the whole surface of the substrate 13.sub.2. This layer is exposed by means of a second exposure mask. After it has been developed the pattern-forming layers of the layer pack 12.sub.2 are applied in succession, including an interference layer 24.sub.2 defining the second color, a high-refracting absorption-free layer 25.sub.2, a low-refracting absorption-free layer 26.sub.2 and a high-refracting absorption free layer 27.sub.2. The remainder of the second photoresist layer together with the layers 24.sub.2 -27.sub.2 lying over it is then removed.

In FIG. 2a, the pattern-forming layers of the layer pack 11.sub.1 are the layers 14.sub.1 -20.sub.1 and for the layer pack 12.sub.1 are the layers 21.sub.1 -27.sub.1. In FIG. 2b, the pattern-forming layers are layers 17.sub.2 -20.sub.2 in the layer pack 11.sub.2 and layers 24.sub.2 -27.sub.2 in the layer pack 12.sub.2. The pattern-forming layers of each layer pack are separate from each other on the substrate.

The present invention may also be made with semifilters as shown in FIGS. 3a and b. Pattern-forming layer pack 31.sub.1 on the substrate 33.sub.1 in FIG. 3a is made of a high-refracting absorption-free layer 34.sub.1, a low-refracting absorption-free layer 35.sub.1, a high-refracting absorption-free layer 36.sub.1, an inorganic interference layer 37.sub.1 defining the first color and a metal layer 38.sub.1. The layers 34.sub.1 -38.sub.1 are the pattern-forming layers of the layer pack 31.sub.1. Pattern-forming layer pack 32.sub.1 on the substrate 33.sub.1 is made of a high-refracting absorption-free layer 39.sub.1, a low-refracting absorption-free layer 40.sub.1, a high-refracting absorption-free layer 41.sub.1, an inorganic absorption-free interference layer 42.sub.1 defining the second color and a metal layer 43.sub.1. The layers 39.sub.1 -43.sub.1 are the pattern-forming layers of the layer pack 32.sub.1.

Referring now to FIG. 3b, the layer pack 31.sub.2 on the substrate 33.sub.2 consists of a high-refracting absorption-free layer 34.sub.2 covering the whole surface, a low-refracting absorption-free layer 35.sub.2 also covering the whole surface, a high-refracting absorption-free layer 36.sub.2, an inorganic absorption-free interference layer 37.sub.2 defining the first color and a metal layer 38.sub.2. The pattern-forming layers of the layer pack 31.sub.2 are the layers 36.sub.2 -38.sub.2. The layers 34.sub.2 and 35.sub.2 cover the whole surface and do not contribute to the pattern formation. The layer pack 32.sub.2 on the substrate 33.sub.2 consists of the whole surface layers 34.sub.2 and 35.sub.2, a high-refracting absorption-free layer 41.sub.2, an inorganic absorption-free layer 42.sub.2 defining the second color and a metal layer 43.sub.2. The pattern-forming layers of the layer pack 32.sub.2 are the layers 41.sub.2 -43.sub.2. The recording mediums of FIGS. 3a and b are generated by photolithographic means as described for the preceding embodiments. The metal layers 38 and 43 are partially permeable layers.

Referring now to FIGS. 4a-d, recording mediums of the present invention are shown using induced transmission filters. In FIG. 4a, the pattern-forming layer pack 51.sub.1 on the substrate 53.sub.1 consists of the following layers in succession: a high-refracting absorption-free layer 54.sub.1, a low-refracting absorption-free layer 55.sub.1, a high-refracting absorption-free layer 56.sub.1, a first inorganic absorption-free interference layer 57.sub.1 in accordance with the first color, a metal layer 58.sub.1, a second inorganic absorption-free interference layer in accordance with the first color, a high-refracting absorption-free layer 60.sub.1, a low-refracting absorption-free layer 61.sub.1 and a high-refracting absorption-free layer 62.sub.1. This sequence of layers corresponds to the first color. The layers 54.sub.1 -62.sub.1 are the pattern-forming layers of the layer pack 51.sub.1. Pattern-forming layer pack 52.sub.1 on the substrate 53.sub.1 consists of a similar arrangement of layers in succession: a high-refracting absorption-free layer 63.sub.1, a low-refracting absorption-free layer 64.sub.1, a high-refracting absorption-free layer 65.sub.1, a first inorganic absorption-free interference layer 66.sub.1 in accordance with the second color, a metal layer 67.sub.1, a second inorganic absorption-free interference layer 68.sub.1 in accordance with the second color, a high-refracting absorption-free layer 69.sub.1, a low-refracting absorption-free layer 70.sub.1 and a high-refracting absorption-free layer 71.sub.1. The layers 63.sub.1 -71.sub.1 are the pattern-forming layers of the layer pack 52.sub.1.

Referring now to FIG. 4b, the layer pack 51.sub.2 on the substrate 53.sub.2 consists of a whole-surface high-refracting absorption-free layer 54.sub.2, a whole-surface low-refracting absorption-free layer 55.sub.2, a whole surface high-refracting absorption-free layer 56.sub.2, a first inorganic absorption-free interference layer 57.sub.2 corresponding to the first color, a metal layer 58.sub.2, a second inorganic absorption-free interference layer 59.sub.2 corresponding to the first color, a high-refracting absorption-free layer 60.sub.2, a low-refracting absorption-free layer 61.sub.2 and a high-refracting absorption-free layer 62.sub.2. The layers 57.sub.2 -62.sub.2 are the pattern-forming layers of the layer pack 51.sub.2, while the whole surface layers 54.sub.2 -56.sub.2 do not contribute at all to the pattern formation. The layer pack 52.sub.2 on the substrate 53.sub.2 consists of a similar arrangement of layers in succession including, the whole surface layers 54.sub.2 -56.sub.2, a first inorganic absorption-free interference layer 66.sub.2 corresponding to the second color, a metal layer 67.sub.2, a second inorganic absorption-free interference layer 68.sub.2 corresponding to the second color, a high-refracting absorption-free layer 69.sub.2, a low-refracting absorption-free layer 70.sub.2 and a high-refracting absorption-free layer 71.sub.2. The layers 66.sub.2 -71.sub.2 are the pattern-forming layers of the layer pack 52.sub.2 while the whole-surface layers 54.sub.2 -56.sub.2 are non-pattern-forming layers which do not contribute to the pattern formation. The recording mediums according to the FIGS. 4a and b are generated by photolithographic means as described for the previous embodiments.

Referring now to FIG. 4c, the process for generating the recording medium there shown shall be described. A first photoresist layer is applied over the whole surface of the substrate 53.sub.3. This layer is exposed by means of a first exposure mask. After the photoresist layer has been developed, the following layers are applied over the whole surface of the substrate 53.sub.3 in succession in a sequence which corresponds to the desired first color, a high-refracting absorption-free layer 54.sub.3, a low-refracting absorption-free layer 55.sub.3, a high-refracting absorption-free layer 56.sub.3, a first inorganic absorption-free interference layer 57.sub.3 corresponding to the first color, a metal layer 58.sub.3 and a second inorganic absorption-free interference layer corresponding to the first color. The remaining first photoresist layer, together with the layers 54.sub.3 -59.sub.3 which are situated over the remaining photoresist, are removed. To generate the second color on the substrate 53.sub.3, a second photoresist layer is applied over the whole surface. This is exposed by means of a second exposure mask. After the second photoresist layer has been developed, the whole surface of the substrate 53.sub.3 is covered by the following layers in succession, a high-refracting absorption-free layer 63.sub.3, a low-refracting absorption-free layer 64.sub.3 , a high-refracting absorption-free layer 65.sub.3, a first inorganic absorption-free interference layer 66.sub.3 in accordance with the second color, a metal layer 67.sub.3 and a second inorganic absorption-free interference layer 68.sub.3 in accordance with the second color. The remaining second photoresist layer, together with the layers 63.sub.3 -68.sub.3 lying over it, is then removed. Left remaining on the substrate 53.sub.3 are the pattern-forming layers 54.sub.3 -59.sub.3 of the first layer pack 51.sub.3 and the pattern-forming layers 63.sub.3 -68.sub.3 of the layer pack 52.sub.3 for the second color. The layer packs and the substrate are now covered with a high-refracting absorption-free layer 60.sub.3, a low-refracting absorption-free layer 61.sub.3, and high-refracting absorption-free layer 62.sub.3. These whole-surface layers 60.sub.3 -62.sub.3 are non-pattern-forming layers which do not contribute to the pattern formation.

Another method for carrying out the present invention results in the recording medium shown in FIG. 4d. A first photoresist layer is applied over the whole surface of the substrate 53.sub.4 and is exposed by means of a first exposure mask. After the layer has been developed, the following layers are successively applied over the whole surface of the substrate 53.sub.4 in a sequence corresponding to the first color: a high-refracting absorption-free layer 55.sub.4, a low-refracting absorption-free layer 55.sub.4, a high-refracting absorption-free layer 56.sub.4 and a first inorganic absorption-free interference layer 57.sub.4 corresponding to the first color. The remaining first photoresist layer, together with the layers 54.sub.4 -57.sub.4 lying over it, are then removed. To generate the second color, a second photoresist layer is applied over the whole surface of the substrate 53.sub.4. The second photoresist layer is exposed by means of a second exposure mask. After it has been developed, the whole surface of the substrate 53.sub.4 is covered by a high-refracting absorption-free layer 63.sub.4, a low-refracting absorption-free layer 64.sub.4, a high-refracting absorption-free layer 65.sub.4 and a first inorganic absorption-free layer 65.sub.4 according to the second color. The remaining second photoresist layer, together with the layers 63.sub.4 -66.sub.4 situated on top of it, is then removed. At this point, remaining on the substrate 53.sub.4 are the first part of the layer pack 51.sub.4 for the first color and the first part of the layer pack 52.sub.4 for the second color. A metal layer 58.sub.4 is applied over the entire surface of the substrate 53.sub.4 and does not contribute to the pattern formation. A third photoresist layer is applied over this layer and is exposed by means of the first exposure mask. After developing the third photoresist layer, the whole surface of the substrate 53.sub.4 is covered by the successive application of the following layers in sequence for producing the first color: a second inorganic absorption-free interference layer 59.sub.4 corresponding to the first color, a high-refracting absorption-free layer 60.sub.4, a low-refracting absorption-free layer 61.sub.4 and a high-refracting absorption-free layer 62.sub.4. The remaining third photoresist layer, together with the layers 59.sub.4 -62.sub.4 lying over it, is then removed. For generating the second color, a fourth photoresist layer is applied over the entire surface of the substrate 53.sub.4 and this is exposed by means of a second exposure mask. After the fourth photoresist layer has been developed, the following layers are applied in succession over the whole surface of the substrate 53.sub.4, a second inorganic absorption-free interference layer 68.sub.4, corresponding to the second color, a high-refracting absorption-free layer 69.sub.4, a low-refracting absorption-free layer 70.sub.4 and a high-refracting absorption-free layer 71.sub.4. The remaining fourth photoresist layer, together with the layers 68.sub.4 -71.sub.4 lying over it, is then removed. The metal layers 58,67 found in FIG. 4a-d are partially permeable layers.

It is also possible to use edge filters in the recording mediums of the present invention as shown in FIGS. 5a and b. A pattern-forming layer pack 81.sub.1 on the substrate 83.sub.1 of FIG. 5a consists of two edge filters 84.sub.1 -88.sub.1 and 89.sub.1 -93.sub.1 lying one over the other. In each edge filter the low-refracting absorption-free layers 85.sub.1,87.sub.1, and 90.sub.1,92.sub.2 are bounded on both sides by the high-refracting absorption-free layers 84.sub.1, 86.sub.1, 88.sub.1, and 89.sub.1,91.sub.1,93.sub.1. The layer pack 82.sub.1 on the substrate 83.sub.1 also consists of two edge filters 94.sub.1 -98.sub.1 and 99.sub.1 -103.sub.1 lying one over the other. Each edge filter consists of high-refracting absorption-free layers 94.sub.1, 96.sub.1, 98.sub.1, 99.sub.1, 101.sub.1, 103.sub.1 between which there are present low-refracting absorption-free layers 95.sub.1,97.sub.1,100.sub.1,102.sub.1. The layers 84.sub.1 -93.sub.1 are the pattern-forming layers of the layer pack 81.sub.1 and the layers 94.sub.1 -103.sub.1 are the pattern-forming layers of the layer pack 82.sub.1.

Referring now to FIG. 5b, the layer pack 81.sub.2 on the substrate 83.sub.2 consists of two edge filters 84.sub.2 -88.sub.2 and 89.sub.2 -93.sub.2 lying one on the other. The edge filter 84.sub.2 -88.sub.2 consists of whole surface absorption-free layers 84.sub.2,86.sub.2,88.sub.2, between which there are present whole surface low-refracting absorption-free layers 85.sub.2,87.sub.2. The edge filter 89.sub.2 -93.sub.2 consists of the high-refracting absorption-free layers 89.sub.2,91.sub.2,93.sub.2, between which there are present low-refracting absorption-free layers 90.sub.2, 92.sub.2. The layers of the edge filter 90.sub.2 -93.sub.2 are the pattern-forming layers of the layer pack 81.sub.2. The layer pack 82.sub.2 on the substrate 83.sub.2 consists of the whole-surface edge filter 84.sub.2 -88.sub.2 over which is present the edge filter 99.sub.2 -103.sub.2. This edge filter 99.sub.2 -103.sub.2 consists of high-refracting absorption-free layers 99.sub.2, 101.sub.2, 103.sub.2 between which are present the low-refracting absorption-free layers 100.sub. 2, 102.sub.2. The layers of the edge filter 99.sub.2 -103.sub.2 are the pattern-forming layers of the layer pack 82.sub.2. The whole surface edge filter 84.sub.2 -88.sub.2 does not contribute to the pattern formation of the layer packs 81.sub.2,82.sub.2.

In the filters 1,2,11,12,31,32,51,52 the first and second color hues are determined by the optical thicknesses of the interference layers 5,8,17,24,37,42, 57,59,66,68. The saturation of these color hues is determined by the reflection capacity of the metal layers 4,6,7,9,38,43,58,67 and respectively of the high-refracting layers 14,16,18,20,21,23,25,27,34,36,39,41, 54,56,60,62,63,65,69,71 and of the low-refracting layers 15,19,22,26,35,40,55,61,64,70. Thus, the layers and their sequence in a layer pack will determine the optical qualities of the resulting color.

In an edge filter (reflector), the spectrum of high transmission declines over a steep slope to a spectrum range of low transmission. The optical thicknesses of the high-refracting and low-refracting layers of an edge filter amount to a quarter wavelength (.lambda./4), where the wavelength (.lambda.) is equal to the greatest wavelength of the least transmission by the edge filter. In FIG. 5a, the edge filters of the first part of the layer packs 84.sub.1 -88.sub.1,94.sub.1 -98.sub.1 display in the range of the two color hues to be generated, a transmission which increases as the wavelength increases. The other edge filters in the second part of the layer packs 89.sub.1 -93.sub.1,99.sub.1 -103.sub.1 display in this range a decreasing transmission as wavelength increases. By the superposition of the edge filters 84.sub.1 -88.sub.1,94.sub.1 -98.sub.1 with the edge filters 89.sub.1 -93.sub.1,99.sub.1 -103.sub.1 there is achieved a maximum transmission for the desired color hues.

At a certain ratio of layer thickness of the edge filters to the size of the spacing between layer packs in the high resolution pattern, difficulties may arise in the removal of the remaining photoresist layer together with the overlying layers. It is preferred, therefore, to form the filters according to FIG. 5b. The lower edge filter 84.sub.2 -88.sub.2 covers the whole surface. The whole-surface edge filter 84.sub.2 -88.sub.2 must in certain wavelength ranges have as high and as constant a transmission as possible. This is achieved by a variation of the optical thicknesses of the high-refracting and low-refracting layers 84.sub.2 -88.sub.2. Preferably, the optical thicknesses remaining within the range of .+-.10% from the amount of a quarter wavelength (.lambda./4), as defined above.

The layer packs may be made as a combination of different filters. Referring now to FIGS. 6a and b, there is shown recording mediums having edge filters and superimposed metal dielectric filters. The layer pack 111.sub.1 on the substrate 113.sub.1 in FIG. 6a, consists of an edge filter 114.sub.1 -118.sub.1 with high-refracting absorption-free layers 114.sub.1,116.sub.1,118.sub.1 between which there are present low-refracting absorption-free layers 115.sub.1 and 117.sub.1. Layer pack 111.sub.1 also includes a metal dielectric interference filter 119.sub.1 -121.sub.1, with an interference layer 120.sub.1 which is bounded on both sides by inorganic reflecting layers 119.sub.1,121.sub.1. The layer pack 112.sub.1 on the substrate 113.sub.1 consists of an edge filter 122.sub.1 -128.sub.1 with high-refracting absorption-free layers 122.sub.1,124.sub.1, 126.sub.1,128.sub.1 between which are low-refracting absorption-free layers 123.sub.1,125.sub.1,127.sub.1. Also included in layer pack 112.sub.1 is a metal dielectric interference filter 129.sub.1 -131.sub.1 having an interference layer 130.sub.1 which is bounded on both sides by inorganic reflecting layers 129.sub.1,131.sub.1. The layers 114.sub.1 -121.sub.1 are the pattern-forming layers of the layer pack 111.sub.1, and the layers 122.sub.1 -131.sub.1 are the pattern-forming layers of the layer pack 112.sub.1.

Referring now to FIG. 6b, the layer pack 111.sub.2 on the substrate 113.sub.2 consists of an edge filter 114.sub.2 -118.sub.2 which covers the whole surface. This edge filter 114.sub.2 -118.sub.2 includes whole-surface high-refracting absorption-free layers 114.sub.2,116.sub.2,118.sub.2 between which there are present whole-surface low-refracting absorption-free layers 115.sub.2,117.sub.2. The layer pack 111.sub.2 also includes a metal dielectric interference filter 119.sub.2 -121.sub.2 having an interference layer 120.sub.2 which is bounded on both sides by inorganic reflecting layers 119.sub.2,121.sub.2. It is the layers of the metal dielectric interference filter 119.sub.2 -121.sub.2 which are the pattern-forming layers of the layer pack 111.sub.2. The layer pack 112.sub.2 on the substrate 113.sub.2 consists of the whole surface layers 114.sub.2 -118.sub.2, a low-refracting absorption-free layer 127.sub.2, a high-refracting absorption-free layer 128.sub.2 and a metal dielectric interference filter 129.sub.2 -131.sub.2. The metal dielectric interference filter 129.sub.2 -131.sub.2 includes an interference layer 130.sub.2 which is bounded on both sides by inorganic reflecting layers 129.sub.2,131.sub.2. The layers 127.sub.2,128.sub.2 and the metal dielectric interference filter 129.sub.2 -131.sub.2 are the pattern-forming layers of the layer pack 112.sub.2.

The inorganic reflecting layers 4,6,7,9,38, 43,58,67,119,121,129,131 are preferably made of silver, chromium, gold or aluminum or some combination of these materials. The interference layers 5,8,17,24,37,42,57, 59,66,68,120,130 are preferably made of MgF.sub.2, SiO.sub.2, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3 or some mixture of these materials. The high-refracting layers 14,16,18,20,21,23,25,27,34,36, 39,41,54,56,60,62,63,65,69,71,84,86,88,89,91,93,94,96, 98,99,101,103,114,116,118,122,124,126,128 are preferably made of TiO.sub.2, ZrO.sub.2, HfO.sub.2, Nd.sub.2 O.sub.3 or some mixture of these materials. The low-refracting layers 15,19,22,26,35, 40,55,61,64,70,85,87,90,92,95,97,100,102,115,117,123, 125,127 are preferably made of MgF.sub.2, SiO.sub.2, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3 or some mixture of these materials. The substrate 3,13, 33,53,83,113 may be made of a transparent material or of an opaque material with a reflecting surface.

The layer packs 1,2,11,12,31,32,51,52,81,82,111, 112 and the pattern-forming layers making up the layer packs are applied successively by photolithographic means. The pattern-forming layers of the layer packs are applied in a sequence to correspond with the color of the layer pack in the high resolution pattern being formed. According to the process of the present invention, the pattern for a plurality of pattern-forming layers in a layer pack is formed simultaneously when the remainder of a developed layer of photoresist is removed along with the layers overlying it. In addition to the photolithographic process described above, it is possible for the layer packs to be generated by means of wet chemical etching processes or physical etching processes such as ion beam etching, sputter etching, plasma etching or reactive ion etching. It is also possible to generate the layer packs or pattern-forming layers of the layer packs by means of a vapor treatment mask or by means of a controlled particle jet, for example an electron or an ion jet.

Several different embodiments of the present invention may be employed on the same substrate. It is possible that on one part of a substrate, layer packs with partially whole-surface layers can be used while on other parts of the substrate layer packs without any whole-surface layers may be employed. It would also be possible to use different production processes on the same substrate. Different layer packs which are generated adjacent one another define a boundary zone between them which identifies the separation between the layer packs.

The recording mediums of the present invention provide the important advantages of improved color hue purity and color hue saturation. There is also a reduction in the number of rejects created using the present methods described above. These recording mediums are ideally suited for the recording of multicolor microtopographical maps.

Of course, it should be understood that various changes and modifications to the preferred embodiments described above will be apparent to those skilled in the art. For example, application of the layers can be carried out by a number of different methods including vaporization, sputtering, ion plating and precipitation from the vapor phase. It is therefore intended that such changes and modifications be covered by the following claims.