JP3893009B2 - Pattern formation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pattern forming method for forming a fine pattern used in a semiconductor device or a micromachine device.
[0002]
[Prior art]
In a semiconductor device, in order to integrate elements at a high density in a smaller area, it is necessary to use a multilayer structure in which elements and wirings are formed more finely and wirings are formed in multiple layers. Also in the micromachine device, a multilayer structure is used to realize a three-dimensional structure. For example, in the manufacture of a micromachine device, a structure to be formed is divided into a plurality of parts in the height direction, and when a lower part is formed, an interlayer film is formed by embedding the periphery of the formed part to form a flat state. The intermediate part is formed by connecting to the lower part already formed above.
[0003]
As a technique for flatly forming an interlayer film etc. on a pattern with unevenness, first, after forming the interlayer film on the unevenness, the convex part of the interlayer film surface reflecting the unevenness is selectively deleted. There is something that flattens. Also, a damascene method is used in which a groove is formed in a flat interlayer film, a pattern is formed by filling the groove with a material for forming a pattern, and the flattened state is obtained when the pattern is formed. There is also a technology called. In the damascene method, a chemical mechanical polishing method (CMP method) is often used to form a state in which the groove is filled with a material.
[0004]
The pattern formation by the damascene method will be briefly described. First, as shown in FIG. 2A, an interlayer film 202 is formed on a substrate 201, and a groove 203a and a groove 203b having a predetermined shape are formed at predetermined positions of the interlayer film 202.
Next, as shown in FIG. 2B, a polyimide resin film 204 is formed on the interlayer film 202 including the groove 203a and the groove 203b, and the groove 203a and the groove 203b are filled with the polyimide resin. To do.
[0005]
Finally, as shown in FIG. 2C, the polyimide resin film 204 is ground and polished by CMP until the surface of the interlayer film 202 is exposed, and the polyimide resin is left only in the grooves 203a and 203b. , 204b. In this CMP, when the polyimide resin is selectively ground and polished with respect to the material of the interlayer film 202, the grinding and polishing can be stopped when the surface of the interlayer film 202 is exposed. In the damascene method, when the pattern is formed in the trench, the upper surface of the pattern and the upper surface of the interlayer film are flattened by forming the same plane, and therefore, it is not necessary to flatten the surface of the interlayer film. In the formation of a micromachine by the damascene method, “interlayer film formation-groove formation-pattern formation” is repeated a predetermined number of times.
[0006]
[Problems to be solved by the invention]
The CMP used in the above-described damascene method is a very effective means when a sufficient polishing selection ratio can be secured between a film to be polished and a film to be polished. Moreover, even if not selectable ratio sufficient polishing, if Migaku Ken target film is thin as about 1μm is effective as a means for flattening.
However, such formation of micromachines, if the target is 10μm about a thick film of polishing by CMP, since the end point determination is very difficult, forced to slow the polishing rate Enaku, it takes a long time to polish .
[0007]
When the film thickness is as thick as 10 μm, the film thickness unevenness also increases. Therefore, when grinding and polishing by CMP, the film to be polished remains in the other area even if it is the end point in one area. Therefore, the end point determination becomes very difficult. Therefore, conventionally, rough cutting is first performed, and finally, final polishing is performed in a state where the polishing rate is extremely slow to improve the polishing selection ratio. As described above, when a flat film is formed by cutting and polishing a thick film of about 10 μm by the CMP method, such as when forming a micromachine using the damascene method, there has been a problem that it takes a very long time.
[0008]
The present invention has been made to solve the above-described problems, and is intended to enable a pattern such as a micromachine to be formed in a shorter time than before by using a damascene method in which planarization is performed by CMP. Objective.
[0009]
[Means for Solving the Problems]
In the pattern forming method of the present invention, a recess is formed in a substrate, and a resin film made of a resin such as polyimide having sensitivity to ultraviolet rays is formed on the substrate by embedding the recess, and the recess is centered on the recess. The resin film is selectively exposed with ultraviolet rays so that the solubility in the developer in the wide first area and the area other than the first area is different, and after this exposure, the resin film is developed with the developer and the first is developed. The first pattern consisting of the first region of the resin film is formed by removing portions other than the region 1, and the portion of the first pattern protruding on the base is selectively ground and polished by the CMP method. The recesses are filled with a second pattern made of resin so as to form one surface. The recess is, for example, a groove extending in a predetermined direction on the substrate (interlayer film) .
According to the present invention, in the course of manufacturing, the first pattern is partially present on the surface of the substrate, the partial first pattern that exists is the grinding and polishing target by CMP.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, as shown in FIG. 1A, an interlayer film (base) 102 having a film thickness of about 10 μm is formed on a substrate 101, and a groove 103a and a groove 103b reaching the substrate 101 are formed at predetermined positions of the interlayer film 102. To do. The interlayer film 102 may be made of polysilicon, for example. In this case, first, the surface of the interlayer film 102 is thermally oxidized to form a thermal oxide film having a thickness of about 1 μm, and then a resist pattern is formed on the thermal oxide film by a photolithography technique, and wet with HF liquid using the resist pattern as a mask. The thermal oxide film is patterned by etching. Next, after removing the resist pattern, the groove 103a, 103b can be formed by selectively removing the interlayer film 102 by wet etching with an aqueous potassium hydroxide solution using the pattern of the thermal oxide film as a mask.
[0011]
Next, a resin film 104 made of polyimide having photosensitivity is formed to a thickness of about 16 μm on the interlayer film 102 in which the grooves 103a and 103b are formed. As the polyimide having photosensitivity, for example, a base resin such as polyimide added with a positive photosensitive agent such as CRC8300 manufactured by Sumitomo Bakelite Co., Ltd. may be used. As the base resin, polyamic acid or polybenzoxazole may be used. When the CRC8300 is used as a photosensitizer, the resin film is formed on the interlayer film 102 by spin coating, and then pre-baking (preheating) at about 120 ° C. is performed for 4 minutes using a hot plate. The organic solvent component in the resin film is removed to some extent.
[0012]
Next, a photomask 121 that shields a region slightly wider than the groove 103a, 103b formation region with the groove 103a, 103b formation region as the center is used, and an ultraviolet ray is selectively applied to a region that is not shielded by the photomask 121 of the resin film 104. 122 is exposed. Thereafter, after a development process using a predetermined developer, the resin is cured by heating and the photosensitive agent is removed. As shown in FIG. 1 (d), a convex pattern (first pattern) is obtained. 104a is formed. In the curing by heating, after being held at 150 ° C. for about 30 minutes in a nitrogen gas atmosphere, it is subsequently held at 310 to 320 ° C. for about 30 minutes.
[0013]
Next, a portion of the convex pattern 104a protruding on the surface of the interlayer film 102 was ground and polished by a chemical mechanical polishing (CMP) method, and the interlayer film 102 was planarized. As a result, as shown in FIG. 1E, predetermined patterns (second patterns) 105a and 105b made of polyimide are formed in the recesses 103a and 103b of the interlayer film 102. The patterns 105 a and 105 b are formed in the groove 103 so as to form one surface together with the interlayer film 102.
[0014]
Thereafter, for example, a predetermined structure is formed on the interlayer film 102 including a part of the patterns 105a and 105b, and after the structure is formed, the pattern 105a made of resin is dissolved in an organic solvent. , 105b can be selectively removed to obtain a state in which a space formed by the groove 103 is formed under the structure. At this time, since the ground state is formed flat, the structure can be formed easily and accurately.
[0015]
In the above-described planarization polishing by the CMP method, a slurry made of alumina was used. The CMP, about 3 minutes, the interlayer film 102 projecting portion on the protruding pattern 104a can be ground and polished. The polishing end point may be a point at which the exposure of the surface of the interlayer film 102 other than the groove 103 can be visually confirmed. In the grinding and polishing by the CMP method, if the surface of the interlayer film 102 made of silicon is exposed, the progress of polishing becomes very slow, and the end point can be easily detected.
[0016]
Unlike the present embodiment, when the CMP for flattening is performed with the resin film formed on the entire area of the interlayer film as in the prior art without forming the convex pattern 104a , rough cutting is first performed at 25. For one minute, and then finish polishing. As described above, when the film is formed thick, the variation in the film thickness also increases.Therefore, when the polishing end point is near, there is a region where the resin film remains thick and a region where the resin film hardly remains. ing. In the final polishing, it is necessary to consider this film thickness variation and the polishing selection ratio between the resin film and the underlying interlayer film, and the polishing rate is very slow. As a result, it took about 55 minutes for the final polishing.
[0017]
Compared with the above-described conventional technique, according to the present embodiment, the time for grinding and polishing by the CMP method can be shortened to about 1/20 or less.
In this embodiment, the object to be polished by the CMP method is a protrusion, and the amount of polishing is small, and it is easy to be polished as a shape effect, which enables quick planarization polishing in about 3 minutes it is conceivable that. For example, when the object to be polished is a convex pattern, polishing proceeds three-dimensionally, but when a flat film is polished, it is considered that polishing proceeds only planarly, which is the difference in polishing rate. it is conceivable that.
[0018]
Further, according to this embodiment, it is easy to end point determination of the polishing, for sufficiently easily secured even polishing selectivity between the polishing target of the pattern and the layer ligament may good uniformity flattened. In this embodiment, the number of objects to be polished is small, and the polishing speed is increased because three-dimensional polishing is performed. Therefore, in the conventional state, the polishing proceeds rapidly even under the condition where the polishing speed is decreased. Therefore, according to the present embodiment, the actual polishing rate does not become slow even if the polishing rate becomes slow in order to improve the polishing selectivity between different materials. As a result, as described above, the planarization can be performed with good uniformity while ensuring a sufficient polishing selection ratio without sacrificing the actual polishing rate.
[0019]
【The invention's effect】
As described above, according to the present invention, on the manufacturing course of the substrate surface, the first pattern is partially present, grinding and polishing target is first patterns present in this part by CMP Therefore, since the amount of polishing is small and polishing is easy as a shape effect, it is possible to form a pattern used for a micromachine or the like in a shorter time than before by using a damascene method in which planarization is performed by CMP. An effect is obtained.
[Brief description of the drawings]
FIG. 1 is a process diagram for explaining a pattern forming method according to an embodiment of the present invention.
FIG. 2 is a process diagram for explaining a conventional pattern forming method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Board | substrate, 102 ... Interlayer film (base | substrate), 103a, 103b ... Groove, 104 ... Resin film, 104a ... Convex pattern (1st pattern), 105a, 105b ... Pattern (2nd pattern), 121 ... Photomask 122 ... UV rays.

Claims (5)

Forming a recess in the substrate;
Forming a resin film made of a resin having sensitivity to ultraviolet rays on the substrate by embedding the concave portion;
A step of selectively exposing the resin film with ultraviolet rays so that the first region wider than the concave portion centered on the concave portion and the solubility in the developer other than the first region are different from each other;
After the step of exposing, the resin film is developed with the developer to remove areas other than the first area, and a first pattern including the first area of the resin film is formed;
A portion of the first pattern protruding on the base is selectively ground and polished by CMP, and the concave portion is filled with the second pattern made of the resin so as to form one surface together with the base. And a pattern forming method comprising: In the pattern formation method of Claim 1,
The pattern forming method, wherein the resin is made of polyimide. In the pattern formation method of Claim 1 or 2,
The pattern forming method, wherein the recess is a groove extending in a predetermined direction on the substrate. In the pattern formation method of any one of Claims 1-3,
The first pattern is a convex pattern and is formed wider than the concave portion. The pattern formation method characterized by the above-mentioned. In the pattern formation method of any one of Claims 1-4,
The base is made of silicon. The pattern formation method characterized by the above-mentioned.

Images