DE2403641A1 - Forming fine patterns - by etching away layer between substrate and resist layer - Google Patents

Abstract

After formation of the resist pattern, a layer between the substrate and resist pattern is etched away to expose the substrate and to form an overhanging portion of the resist pattern due to lateral etching of the intermediate layer. The etched body is coated, the coating covering the exposed substrate and the resist layer but not filling the space beneath the resist pattern overhang. This leaves a very fine clearance between the intermediate layer and the coating. The resist pattern and the coating covering it can be removed by dissolution of the resist pattern. If two layers are provided between the substrate and the resist pattern a second etching process can be effected for forming in addn to very fine clearances between the intermediate layer and coating, very fine structures of coating material on the substrate.

Description

Method of Making Fine Patterns The invention relates to a process for the production of fine patterns (templates or stencils), them relates in particular to a method for producing originals with a high Accuracy as well as the products available, in particular an electrode with Comb structure and a method for its manufacture.

For the production of patterns or templates or scraping ions are used previously used various methods, such as photolithography, Auf drawing and photoresist processes. The accuracy of using this However, the method of producing samples or templates is limited. For example the resolution in photolithography (light printing process) about 1 M or the like. 7 are the diffraction of light and the resolution of photographic materials however limited1 and it is therefore no higher resolution than corresponding to this Limit value to be expected. Even if the problems of diffraction of light and the Dissolution of the photographic materials must be resolved, recording intervals of about 2 P or the like.

are complied with because of the limited recording accuracy. In addition, it is known that even when using a photomask with a high resolution in any way can be produced, the dissolution in the stage in which creates the resist image in a photoresist process using the photomask decreases to about 2 p or the like.

The aim of the present invention is therefore to provide an improved method for the production of samples (templates or templates) with a high degree of accuracy, Specify in particular for the production of extremely fine samples (templates, stencils). Another aim of the invention is to develop a self-aligning method for manufacturing to indicate such patterns.

It has now been found that these objects can be achieved according to the invention can with the help of a process for the production of fine patterns (templates, Templates), which is characterized by the combination of the following levels: (1) Forming a resist pattern on a pattern forming material which consists of at least two layers that are different from the same etchant Dissolve or etch speeds, (2) etch a layer of the pattern forming material with an etchant that forms the adjacent layer and the resist pattern does not dissolve, partially exposing the adjacent layer, and (3) applying a substance insoluble in the etchant in the form of a layer on the whole Surface of the etched material, creating the etched layer of the forming the pattern Material is held in such a way that it does not come into contact with the coating substance, whereby if necessary, step (2) or steps (2) and (4) are repeated.

The subject of the I ~ 2 invention is also one produced by this method Electrode with a kamia structure, as well as a method for producing an electrode with a comb structure with an electrode connection terminal or a coupled charging device (charge coupled device) on a substrate using the above Procedure.

Other objects, features and advantages of the invention will be apparent from the following Description in conjunction with the accompanying drawings.

Figures 1 to 35 of the accompanying drawings illustrate various ones Stages of the basic process according to the invention and preferred embodiments thereof. Preferred embodiments of the invention are described below with reference to FIG the accompanying drawings explained in more detail.

First, a disk W1 having a structure as shown in FIG. 1 is made is produced according to the invention.

In Fig. 1, the plate W1 consists of a substrate 1 and the to etching layer 2. In the figures of the accompanying drawings, there is the substrate made of glass, but it can also consist of silicon if the method according to the invention is applied to an IC device, for example. In principle, any Material such as sapphire, germanium, gallium arsenide, indium antimonide, or a polyethylene terephthalate plastic film besides glass and silicon used in the embodiment described here can be used as a substrate. The layer 2 to be etched is in the figures of the accompanying drawings is a thin layer of metal, it but can also a thin layer of a semiconductor or a Isolator can be used. Examples of suitable metal layers are those of Al, Cr, A # g, Cu, Ni, Co, Au, Pt, Be, Ti, Bi, e, Pb, Sn, Mo, Ni-Cr, Fe-Ni, Fe-Ni-Cr and the like

Examples of suitable semiconductors used according to the invention are Si, Ge, Se, GaAs, GaP, GaSb, InSb, CdS, ZnO, TiO2 and the like. And Examples of suitable insulators are SiO2, A12O3, Fe2O3, Cr2O3 and the like.

The glass used as the substrate 1 and the layer to be etched 2 thin metal layers used have extremely different solubilities with respect to each other on the same etching agent (the etching solution). The by the present invention The results obtained are the better, the greater the difference in solubility between the two layers 1 and 2 is opposite to the same etchant. In relation to the above description the plate 71 corresponds to the material forming the pattern, the layer 2 to be etched corresponds to a layer of the material forming the pattern (In the figures of the accompanying drawings only one layer is shown, it If desired, however, two or more layers can of course also be used) and the substrate 1 corresponds to the adjacent layer (neighboring layer).

Which etching solutions can be used depends of course on the materials used in the configurations used. Suitable examples are given in the following table.

With- Layer 1 Layer 2 etching solution play ~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~ 1 1 glass, sapphire, PET, SiO2 Al phosphoric acid and nitric acid 2 SiO2, sapphire, glass, PET Cu iron (III) chloride 3 Glass, sapphire, SiO2? PET Cr, Cr2O3 Ceric ammonium nitrate + perchlorate 4 SiO2, sapphire, glass, PET Fe2O3 hydrochloric acid 5 SiO2, sapphire, glass, PET Si nitric acid 6 SiO2, sapphire, glass, PET PVAC methyl alcohol 7 Si SiO2 buffered HF (HF + NH42) Based on the information given above, the expert can Easily select the appropriate etching solutions in each case.

In FIG. 1, the resist image is on the layer 2 to be etched forming layer 3 (e.g. a photosensitive polymer layer) is provided.

2 shows the production of a resist layer 3 'after exposure of the layer 3 forming the resist image by a layer 3 applied Photomask. In this Fig. 2, as the resist image-forming layer #IER Q'Kodak-Metal-Etch-Resist ", Trade name for a natural polyisoprene from Eastman Kodak Co.) and this will be used in the following explanation. This level can can thus be carried out entirely analogously to the usual photoresist process. In detail after exposure to ultraviolet light, the material is treated with the KMER developer (Trade name for a product made by Eastman Kodak Co.) developed the non-exposed Remove photoresist layer, and then the material is post-drying subjected. Instead of the above-described photoresist material, an X-ray resist, an electron beam resist and the like for production the resist layer can be used. A1-alternatively, KTFR (Todak Thin Film Resists' Trade name for a synthetic polyisoprene from Eastman Kodak Co.), KPR (Todak Photo Resist ', trade name for polyvinyl cinnamon acid made by the company Eastman Kodak Co.) and AZ-1350 (trade name for a mixture of quinonediazide and a novol resin from Shipley Co.). A suitable developer for KEER and KTFR is xylene.

Thereafter, the layer 2 to be etched is etched. In this etching stage an etchant used for etching the layer 2, which the layer 1 and the layer 3 'does not solve. If as layer 1 glass, as layer 2 aluminum and as layer 3 KEER are used, for example, an etchant can be used that from phosphoric acid 1 nitric acid and water in a weight ratio of 80: 4: 16 consists. The etching runs vertically to layer 2 and also horizontally (transversely) in addition, i.e. after the etching in the horizontal direction, the surface of the layer 1, the etching only proceeds in the transverse direction.

After the etching depth has reached the desired degree in the horizontal direction, for example about 0.5 P or the like. ' has reached (the depth and shape of the etched Layer must necessarily be such that if there is one in the etchant used insoluble substance in the subsequent stage in the form of a layer on the material is applied, the etched layer is not in contact with the substance, what referred to as a side etch ", and this is a major factor in the present invention), the etching is stopped, leaving a plate W3 with a Cross section as shown in Fig. 3 is obtained.

In the subsequent step, a substance insoluble in the etchant becomes 4, e.g. a metal such as aluminum in the form of a layer on the entire surface the plate W3 applied.

In addition to Al, Cr, Cu, Ni, Co, Ag, Sn, Au, Mo, Pt, Be, Ti, Pb, Bi, Te, Ni-Cr, Fe-Ni and Fe-Ni-Cr be used. Substance 4 can, depending on the purpose and use of the pattern formed (template, Template) and it is important that the substance 4 is used in the Etchant is insoluble. The thickness of the substance to be applied in the form of a layer 4 can optionally in this stage-stage-according to the nature of the substance and the required resolution and the like. Be determined and it can, for example be about 0.5M. In this way, a plate W4 as shown in FIG. 4 becomes is received.

The last stage consists in removing the resist layer 3 ' will. After placing the plate W4 of FIG. 4 in a solvent solution for 10 minutes from 950 C, for example J-100 Resist Strip (trade name of Industry Chemical Laboratory Co.), the resist layer 31 can be dissolved and removed a plate WS with a cross-section as shown in FIG. 5 is shown.

The conventional photolithography and photoresist processes The minimum line width obtainable is the width of the opening shown in FIG D, while the minimum width achievable according to the invention is the width of the width shown in Fig. 5 illustrated is-. The width d can be freely reduced if necessary will. That is, the width d can be freely determined by appropriate control the depth of the etching of the layer 2 in the horizontal direction, as described above is. In addition, the line width L of the substance 4 in FIG. 5 can be changed by repetition the method described above, as explained in more detail below, reduced will.

An embodiment of the invention is explained in more detail below, in which the method according to the invention is applied to the production of electrodes with a carnine structure is applied.

The same plate W1 as in Fig. 1 is exposed to ultraviolet light irradiated using a photomask with a pattern as shown in FIG is. The hatched portion of Fig. 6 represents an opaque area other than ultraviolet Lets pass light while the other part is transparent and ultraviolet light lets through. Using the same steps as above for the basic procedure have been described, the electrodes shown in FIG. 7 are obtained with a Embankment structure. After these stages, the opening 5 between the electrodes can become extreme be made narrow.

Another method is explained below in which not only the opening of the electrodes, but also the width of the electrodes themselves decreased can be.

Fig. 8 shows a plate W8 made of a substrate 1, for example glass, the layers of copper 2 and aluminum 2 'to be etched and one a resist image forming layer 3 consists. Following the basic procedure described above, received a plate W9. The opening d between the electrodes and the width L. of the electrodes are the same as in Fig. 5. In this case, the photoresist material removed with acetone.

In the next stage, the copper layer 2 is etched. With an etchant for the layer 2 it must necessarily be one that the layer 1 and the layer 2 'does not dissolve, and a chromic acid mixture, for example, can be used for this purpose (containing 240 g CrO, 40.5 g Na2SO4 and 180 g 96% H2S04 per liter of solution) will. In this etching, the depth in the horizontal direction becomes analogous controlled as described in the basic procedure. This will make a record "like her shown in Fig. 10 is obtained.

Subsequently, copper is applied as substance 4 in the form of a layer applied to the entire surface of the plate W10. The thickness of the plating copper should suitably be almost the same as the sum of the thicknesses of the etched layers 2 and 2 '. A plate W11 as shown in Fig. 11 is obtained.

The last stage consists in applying the layer, analogous to the basic procedure 2 'to loosen and remove. To be used for the removal of the layer 2 ' Liquid must necessarily be one that forms the layer 2 does not dissolve and it is expedient to have one that removes the layer 1 does not solve. An aqueous sodium hydroxide solution, for example, can be used as such a liquid be used. A plate W12 as shown in Fig. 12 is thereby obtained is. In the plate W12, the opening t between the electrodes and the electrode width can be set 1 and d by appropriately controlling the depth in the horizontal direction as in that Basic procedures are described, adjusted to the desired extent (e.g. on 1 = d, 1 = d = t. = 0.5 ft or 1 ##.

As described above, the structure of the plate and the composition of the etchant is selected so that the pattern obtained in the basic process is a resist pattern can be.

In the embodiment described here, the important conditions of the Basic Procedure as such.

Another embodiment is described below, according to which the embodiment shown in Figures 8 to 12 on the production of Electrodes with a comb structure is applied.

After the basic procedure, the photomask is used the 6 and the plate W8 of FIG. 8, the same pattern as in FIG. 7 is obtained. Thereafter are made by repeating those described above with respect to Figures 10-12 Step electrodes with a comb structure as shown in FIG. 13 are obtained are. When the outside of the openings 5 and 6 arranged electrodes 7 and 8 with each other be electrically connected to form a homopolar electrode, while the Electrode 9 between openings 5 and 6 made into a heteropolar electrode becomes, the electrode density is twice that shown in FIG Electrodes. For example, an electrode width of 1 P and a Opening between the electrodes of 0.5 P can be selected.

Another embodiment of the invention is explained below, in which the method according to the invention is based on the production of a coupled 3-phase charging device (3-phase CCD) is applied.

The plate W14 shown in FIG. 14 consists of a substrate 1, for example a silicon single crystal, and a layer 2 to be etched, for example a thin SiO2 layer. A metal layer is also placed on the SiO2 layer 2, e.g. an aluminum layer, applied as a further layer 2 'to be etched. Instead of Of aluminum, other non-corrosive metals such as molybdenum can also be used will. After a layer forming a resist image, e.g. made of KMER, on the metal layer 2 'has been applied, is obtained according to the basic method using the The photomask of FIG. 15 has a pattern as shown in FIG. In Fig. 15, the hatched part represents an opaque area other than ultraviolet Lets light through while the other part is a transparent area, that can transmit ultraviolet light. As shown in Fig. 17, on the SiO2 layer of the plate electrodes A, B, C, B ', A, B, C, B' ... are generated.

It is assumed that an electrical potential V1 is applied to the electrode A is applied and that first under the electrode A, as shown in Fig. 1.7, a potential well is created. If now a potential V2 (IV2l> IV1l) applied to electrodes B and B 'arise on both sides of the electrode A (or under the electrodes B and B ') larger potential wells. However, if the Width B 'is made smaller than the width B, the potential width is below of electrode B 'is smaller than under B and therefore the electric charge flow is from the potential well under the electrode A to the potential well under B is larger as the electric charge flow to the potential well under electrode B 'and especially the electric charge flows in the direction A B C when an electric Voltage is applied to A, B and C in that order.

In the above-described Figures 6, 7ß 15 and 16 is only one Gebil of the electrode shown. To now complete the manufacture of the electrode, the electrode connection terminal must be established. The connection of the electrode In the case of the manufacture of electrodes with an embankment structure, the following can be done: if an electrode with a comb structure is made, the two terminals 2 <and T2 as shown in Fig. 30, a photomask is first used, as shown in Fig. 31.

In Fig. 31, a is slightly larger than b. That with reference to the The method described in FIGS. 1 to 5 is carried out using this photomask, then the metal innister shown in Fig. 32 is produced. The one indicated in FIG Distance g satisfies the relationship a = 2 g + b. In other words, a and b are chosen to satisfy this relationship. Then using another photomask similar to that shown in Fig. 33, the excess metal removed. That is, it will be a photoresist material in Form a layer on top of that entire surface of the metal pattern of Fig. 32 is brought up, a photomask as shown in Fig. 33 is applied the surface is laid, then the photomask is exposed to ultraviolet light and development and etching are carried out. At this point it can be easy an alignment of the mask in the horizontal direction of the electrode, as shown, but it is very difficult in the vertical direction of the electrode perform.

If the mask is not aligned well, it will be different Width of the electrode at the two ends from each other and this is a disadvantage. If the photomask is not transparent, mask alignment is very difficult and sometimes this alignment has to be repeated several times. In the above However, the alignment of the mask can be carried out very easily and is practically a self-alignment overall. Eventually that will Photoresist removed. in the procedure described above The electrode spacing stage is ultimately a self-alignment, however, there is an alignment at the step of removing the excess metal the mask required. However, the problem described above arises in this case on. However, this problem can be eliminated as follows: instead of the one shown in Fig. For example, the photomask shown in FIG. 31 becomes the photomask shown in FIG used. This mask of FIG. 34 has the designations at the tips of the two ends 1, Y and Z and the width H of the photomask of Fig. 33 is made slightly larger. The consequence of this is that an electrode pattern like this is ultimately obtained in Fig. 35 even if the photomask is in the stage of mask alignment something can slide (slide). The dotted line indicates the position where the photomask is on. The width of the two insulated electrodes E and F is small and since they are overturned from the other side, they are not subject to any disadvantage Influence.

The basic method according to the invention can also be applied to the production of a test pattern must be applied at a high resolution.

The plate W18 of Fig. 18 is made of a substrate, for example 1, e.g. glass, and a layer 2 to be etched, e.g. a thin copper layer, which lies on the substrate layer 1. The plate W19 of FIG. 19 is obtained after Photoresist process from the plate W18, wherein the layer 2 is etched and a Resist layer 3 'remains thereon. With this etching, the depth of the etched Copper is set to about 0.5 P in the horizontal direction. Then, after copper as substance 4 in the form of a layer on the entire surface of the Plate W19 has been applied, the resist layer 3 'is removed to form the Plate W20 of Fig. 20.- The plate W20 has a periodic pattern in which the line width in the transparent area about 0.5 P and the line width in the qpaken area is about 3 P. Chrome can be added to reinforce this pattern the copper layer can be plated on or chromium can otherwise be in the form of a Layer can be applied as substance 4 instead of the copper, being the same Procedure is carried out.

The method according to the invention also includes modifications where each stage as described in the previous embodiments has been repeated, and through this repetition, even finer ones can be achieved Gestsuster are received.

The plate W21 shown in Fig. 21 consists of a substrate 1, e.g. glass, and layers to be etched; e.g. a copper layer 2 and an aluminum layer 2 '* A plate W22 having a resist layer 3' is obtained by a photoresist method and after an etching treatment (e.g.

using an aqueous sodium hydroxide solution as Etchant), if there is a photo mask on the aluminum layer 2 '(width of the transparent area: 5 ji, width of the opaque area: 3) is used. This treatment is it is important to determine the depth of the etched aluminum layer 2 'in the horizontal direction to be controlled in a suitable manner during the etching of the aluminum layer 2 '.

Subsequently, after the aluminum 4 is in the form of a layer on the entire surface of the plate has been applied, the resist layer 3 'is removed forming the plate W23 of Fig. 23. Thereafter, the copper layer 2 is etched, wherein the depth is controlled in the horizontal direction to form a plate W24 as shown in FIG. Eventually copper will be 4 'in the shape of a Layer is applied to the entire surface of the plate w24 and then the Aluminum layer 2 'and layer 4 removed to form plate W25 such as it is shown in FIG. This production is ultimately the one obtained plate W2i when the depth of both the aluminum layer 2 'and the Copper layer 2 in the horizontal direction on 1 jl. is set to a test pattern with alternating transparent and opaque lines 1 su wide. The depth each layer in the horizontal direction can if desired by appropriate selection the composition of the etchant and the etching time and temperature can be controlled.

In addition to the embodiments described above, the present invention includes Invention also includes the following embodiment: if, for example, a photoresist material of the negative type is used, the side walls of the resist layer 3 'have one Cross-section as shown in Fig. 26 (bench-like cross-sectional view). This is upon it. For example, the fact that the light irradiation also affects the lower sides reached near the ends of the photomask pattern due to the scattering and Reflection of light, so that the width of the developed in the Resist layer formed pattern is smaller than that of the original photomask pattern (this width is smallest on the surface of the layer 2 to be etched, the is provided on the substrate 1). In this case it is sufficient to determine the depth of the etched layer 2 in the horizontal direction in a suitable manner according to the to control the stages described above. If, on the other hand, a photoresist layer of the positive gp is used, the width of the resist layer pattern 3 'is larger than that of the original phototask pattern as shown in FIG (cross-sectional view - in the form of an inverted bank). (This width is the greatest on the surface of the layer 2 to be etched, which is applied to the substrate 1 has been). Accordingly, it is practically unnecessary to reduce the depth of the etched Control layer 2 in the horizontal direction during the etching of layer 2. The following steps correspond to the method and substance described above 4 is applied in the form of a layer to finally obtain a fine pattern. Application of the present invention to the photoresist described herein of positive type represents a specific embodiment of the invention Method. The cross-section in FIG. 28 is shown in FIG.

usually obtained if an exposure instead of ultraviolet light is applied with an electron beam.

The invention has been described above with reference to specific Embodiments explained in more detail, but it is clear to those skilled in the art that these can be changed and modified in many ways without this. the scope of the present invention is departed from.

Patent claims:

Claims (20)

P a t e n t a n 5 p r ü c h # e 1. Process for the production of fine Patterns characterized by the combination of the following stages: (1) Manufacturing a resist pattern on a pattern-forming material composed of at least consists of two layers that are in the same etchant at different speeds dissolve, (2) etching a layer of the material forming the pattern with an etchant, which does not dissolve the adjacent layer and the resist pattern, with partial exposure this adjacent layer and (3) applying one insoluble in the etchant Substance in the form of a layer on the entire surface of the etched material, whereby the etched layer of the material forming the pattern is held so that it does not come into contact with the coating substance. 2. The method according to claim 1, characterized in that the step (2) is repeated. 3. The method according to claim 1, characterized in that the steps (2) and (3) are repeated. 4. The method according to at least one of claims 1 to 3, characterized characterized in that a plate is used as the material forming the pattern, which consists of a layer to be etched and a substrate. 5. The method according to claim 4, characterized in that the substrate a semiconductor or an insulator and a thin metal layer as the layer to be etched, a thin semiconductor layer or a thin insulator layer can be used. 6. The method according to at least one of claims 1 to 5, characterized characterized in that a resist pattern is applied to the layer to be etched before the etching forming layer is applied. 7. The method according to claim 6, characterized in that as a The layer forming the resist pattern uses a light-sensitive polymer layer will. 8. The method according to at least one of claims 5 to 7, characterized characterized that the metal layer is an aluminum, chromium, Eupfer, nickel, Cobalt, molybdenum, silver, tin, gold, platinum, titanium, beryllium, bismuth, Lead, tellurium, iron-nickel alloy or iron-nickel-chromium alloy layer and as the polymer layer a polymer layer sensitive to ultraviolet light be used. 9. The method according to claim 8, characterized in that the metal layer an aluminum layer is used. 10. The method according to at least one of claims 1 to 9, characterized characterized in that an etchant is used which is phosphoric acid, nitric acid and contains water. 11. The method according to at least one of claims 1 to 10, characterized characterized in that a metal is used as the substance insoluble in the etchant will. 12. The method according to claim 11, characterized in that aluminum is used as the metal. N e u e P a t e n t a n s p r ü c h e 13 - 20 13. Proceedings according to Claim 6 and / or 7, characterized in that as a resist pattern forming layer a negative type photoresist layer is used. 14. The method according to claim 6 and / or #, characterized g e -k e n nz e i n e t that as a resist pattern forming layer, a photoresist layer of the positive type is used. 15. The method according to at least one of claims 1 to 14 for production an electrode with a comb structure which has an electrode connection terminal, or a coupled charging device on a substrate, g e -k e n n z e i c h n e t by combining the following steps: (1) making one of the electrode with chimney structure with an electrode terminal or the coupled charging device corresponding resist pattern on a pattern-forming material composed of at least consists of two layers that are in the same Etchant with different Schwindigke iten solve, with the resist pattern including the outermost teeth and the base of the comb structure opposite the connector or the outermost portions of the coupled charging device are small resist extensions parallel to the base of the structure or device, (2) etching a layer of the material forming the pattern with an etchant, which is an adjacent Layer and the resist pattern does not dissolve, partially exposing these adjacent ones Layer, (3) applying a substance insoluble in the etchant in the form of a layer on the entire surface of the etched material, .which the etched layer of the the pattern-forming material is held so that it is covered with the coating substance does not come into contact, (4) removing the resist pattern, (5) removing the not required coating surfaces from the coating substance with the formation of a photoresist layer on the required surfaces of the electrode structure or the coupled charging device and etching away unnecessary areas and (6) removing the photoresist layer. - 16. The method according to at least one of claims 1 to 3, characterized Note that a positive resist pattern is used as the resist pattern will. 17. Fine pattern, in that it is not shown the method according to at least one of claims 1 to 12 has been produced. 18. Fine pattern according to claim 17, characterized in that g e k e n n -z e i c h n e t that it is designed as an electrode with a comb structure. 19. A fine pattern according to claim 17, characterized in that it is g e k e n n -z e i c h n e t that it is designed as a coupled 3-phase charging device. 20. Fine pattern according to claim 17, characterized in that g e k e n n -z e i c h n e t that it is designed as a test pattern with high resolution.