阅读说明：本技术 生成补偿器的方法 (Method for generating compensator ) 是由 张云雪 宋丹 何玉国 张钱依 黄安琳 于 2021-10-08 设计创作，主要内容包括：本申请公开了一种生成补偿器的方法,涉及光学的技术领域,本申请的生成补偿器的方法,包括在基底上进行镀膜,形成辅助膜层；在辅助膜层上进行涂胶、曝光和显影,形成原始图案；采用预设气体刻蚀显影后的辅助膜层,并在刻蚀到达基底时,继续刻蚀预设时间段后,停止刻蚀,生成计算全息图；其中,基底的材料与辅助膜层的材料不同,预设气体在基底上的刻蚀速率与在辅助膜层上的刻蚀速率不同。故本申请通过在基底上增加辅助膜层,避免了在离子刻蚀过程中,由于刻蚀腔内不同区域离子浓度不同和其它刻蚀参数不同而导致的刻蚀速率不同,进一步避免了由于不同区域的刻蚀深度不均匀,而影响计算全息图的波前精度。(The application discloses a method for generating a compensator, which relates to the technical field of optics and comprises the steps of coating a film on a substrate to form an auxiliary film layer; coating glue, exposing and developing on the auxiliary film layer to form an original pattern; etching the developed auxiliary film layer by adopting preset gas, and stopping etching after continuously etching for a preset time period when the etching reaches the substrate to generate a calculation hologram; the material of the substrate is different from that of the auxiliary film layer, and the etching rate of the preset gas on the substrate is different from that on the auxiliary film layer. Therefore, the auxiliary film layer is added on the substrate, the condition that the etching rate is different due to different ion concentrations and other etching parameters in different areas in the etching cavity in the ion etching process is avoided, and the condition that the wavefront accuracy of the computed hologram is influenced due to the fact that the etching depths of the different areas are not uniform is further avoided.)

1. A method of generating a compensator, comprising:

coating a film on a substrate to form an auxiliary film layer;

gluing, exposing and developing the auxiliary film layer to form an original pattern;

etching the developed auxiliary film layer by adopting a preset gas, and stopping etching after continuously etching for a preset time period when the etching reaches the substrate to generate a calculation hologram;

the material of the substrate is different from that of the auxiliary film layer, and the etching rate of the preset gas on the substrate is different from that on the auxiliary film layer.

2. The method of claim 1, wherein the developing on the auxiliary film layer to form an original pattern comprises:

spin-coating a photoresist on the auxiliary film layer;

and exposing and developing the photoresist by using a mask plate with a preset pattern.

3. The method of claim 1, wherein after the etching the developed auxiliary film layer with the predetermined gas and continuing to etch the substrate for a predetermined period of time, stopping the etching to generate the holographic pattern, further comprising:

and removing the residual photoresist on the auxiliary film layer.

4. The method as claimed in claim 1, wherein the substrate is made of glass BK7, and SiO in BK7₂The content of (A) is 65-73%.

5. The method of claim 4, wherein the auxiliary film layer is made of quartz, and SiO is contained in the quartz₂The content of (A) is more than 99%.

6. The method of claim 5, wherein the predetermined gas has an etch rate of less than 10nm/s on the substrate.

7. The method of claim 6, wherein the etching rate of the predetermined gas on the auxiliary film layer is greater than 40 nm/s.

8. The method of claim 1, wherein the predetermined gas is CHF₃And/or CF₄And O₂The mixed gas of (1).

9. The method of any one of claims 1 to 8, wherein the auxiliary film layer has a thickness in the range of 300nm to 600 nm.

10. The method of claim 2, wherein the photoresist has a thickness in the range of 300nm to 800 nm.

Technical Field

The present application relates to the field of optical technology, and in particular, to a method of generating a compensator.

Background

The reflector with large caliber and complex curved surface (such as aspheric surface, off-axis aspheric surface, free-form surface and the like) is a core element of a space-to-ground high-resolution optical remote sensor. Due to the extremely high requirement on surface shape precision, the processing and detection of the complex curved surface reflector face huge challenges. The detection technology is generally zero detection and non-zero detection, a zero compensator (Null lenses) in the zero detection technology is widely applied, and the Null lenses can be divided into lens type Null lenses and diffraction type Null lenses according to the working principle.

The diffraction type Null lens mainly adopts a Computer Generated Hologram (CGH for short) as a compensator, and compared with the traditional compensator, the CGH detection method can theoretically generate any wavefront and has the advantages of small design residual error, simple structure, no assembly error, short manufacturing period, flexible design and the like.

The CGH can be divided into an amplitude type and a phase type according to a manufacturing process. The diffraction efficiency of the diffraction order used by the amplitude type CGH is low, and the amplitude type CGH is only suitable for detecting materials with high surface reflectivity, such as silicon carbide and silicon. In order to improve the contrast of fringes in the detection process, a phase type CGH is required to be used for aspheric lenses with low reflectivity, such as microcrystalline glass, fused quartz and other materials, but more processing errors, such as etching depth uniformity errors, are introduced into the phase type CGH.

Disclosure of Invention

An object of the present application is to provide a method for generating a compensator to improve the uniformity of the etching depth of a phase type CGH.

A first aspect of an embodiment of the present application provides a method for generating a compensator, including: coating a film on a substrate to form an auxiliary film layer; coating glue, exposing and developing on the auxiliary film layer to form an original pattern; etching the developed auxiliary film layer by adopting a preset gas, and stopping etching after continuously etching for a preset time period when the etching reaches the substrate to generate a calculation hologram; the material of the substrate is different from that of the auxiliary film layer, and the etching rate of the preset gas on the substrate is different from that on the auxiliary film layer.

In an embodiment, the developing on the auxiliary film to form the original pattern includes: spin-coating a photoresist on the auxiliary film layer; and exposing and developing the photoresist by using a mask plate with a preset pattern.

In an embodiment, after the etching the developed auxiliary film layer with the preset gas and continuing to etch for a preset time period when the etching reaches the substrate, the etching is stopped, and after a holographic pattern is generated, the method further includes: and removing the residual photoresist on the auxiliary film layer.

In one embodiment, the substrate is made of a glass material BK7, and SiO in BK7₂The content of (silicon dioxide) is 65-73%.

In an embodiment, the auxiliary film is made of quartz, and the SiO in the quartz₂The content of (silicon dioxide) is more than 99%.

In one embodiment, the etching rate of the predetermined gas on the substrate is less than 10 nm/s.

In an embodiment, an etching rate of the predetermined gas on the auxiliary film is greater than 40 nm/s.

In one embodiment, the predetermined gas is CHF₃And/or CF₄And O₂The mixed gas of (1).

In one embodiment, the thickness of the auxiliary film is in a range of 300nm to 600 nm.

In one embodiment, the photoresist has a thickness in the range of 300nm to 800 nm.

Compared with the prior art, the beneficial effect of this application is:

the method for generating the compensator comprises the steps of firstly coating a film on a substrate before etching the substrate, selecting an auxiliary film layer material which is different from the substrate material and is easier to etch, and utilizing the characteristic that the rates of different materials etched by preset gas are different, so that the etching depth of the compensator is controllable.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a flowchart illustrating a method for generating a compensator according to an embodiment of the present application.

Fig. 2 is a flowchart illustrating sub-steps of step 120 according to an embodiment of the present application.

Fig. 3 is a schematic diagram of a process for generating a compensator according to an embodiment of the present application.

Fig. 4 is a schematic diagram of a process for generating a compensator according to an embodiment of the present application.

Fig. 5 is a schematic diagram of a process for generating a compensator according to an embodiment of the present application.

Fig. 6 is a schematic diagram of a process for generating a compensator according to an embodiment of the present application.

Fig. 7 is a schematic diagram of a process for generating a compensator according to an embodiment of the present application.

Fig. 8 is a schematic diagram of a process for generating a compensator according to an embodiment of the present application.

Reference numerals:

icon: 1-a compensator; 2-a substrate; 3-auxiliary film layer; 4-photoresist.

Detailed Description

The terms "first," "second," "third," and the like are used for descriptive purposes only and not for purposes of indicating or implying relative importance, and do not denote any order or order.

Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present application, it should be noted that the terms "inside", "outside", "left", "right", "upper", "lower", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that are conventionally arranged when products of the application are used, and are used only for convenience in describing the application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the application.

In the description of the present application, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements.

The technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings.

Please refer to fig. 1, which is a flowchart illustrating a method for generating a compensator 1 according to an embodiment of the present application. The method comprises the following steps:

step 110: and coating a film on the substrate 2 to form an auxiliary film layer 3.

In the above steps, as shown in fig. 3, glass can be selected as a material of the substrate 2, such as BK7, BK7 is a common borosilicate crown glass, widely used as an optical material in the visible and near infrared regions, BK7 is excellent in mechanical properties, has excellent scratch resistance, and since BK7 is chemically stable, grinding and polishing are not required for special treatment, permeability in the visible spectrum is excellent, bubbles and impurities are less, and streaks adversely affecting the optical system and unevenness in refractive index are reduced to a level where they hardly affect the optical system. Therefore, BK7 is used in most optical elements such as a mirror or a spectroscope substrate or various kinds of coated filter substrates in addition to a lens or a prism.

In one embodiment, as shown in FIG. 4, quartz may be used as the material of the auxiliary film 3, and the thickness of the film may be in the range of 300nm to 600 nm.

Step 120: and gluing, exposing and developing the auxiliary film layer 3 to form an original pattern.

In the above steps, the original pattern may be an original pattern of a phase-type computation hologram, and in order to achieve high diffraction efficiency, it is necessary to fabricate the phase-type computation hologram on the compensator 1, and the fringe density and fringe position on the original pattern of the phase-type computation hologram can comprehensively record the amplitude and phase of the optical wave, and can synthesize a complex object hologram, thereby having great flexibility.

In an embodiment, as shown in fig. 2, step 120 may specifically include:

step 121: and spin-coating photoresist 4 on the auxiliary film layer 3.

In the above step, the photoresist 4 may be a negative photoresist 4 or a positive photoresist 4. As shown in fig. 5, the thickness of the photoresist 4 may range from 300nm to 800 nm.

Step 122: and exposing and developing the photoresist 4 by using a mask plate with a preset pattern.

In the above steps, the exposed developed structure is shown in FIG. 6, and the pattern of the reticle is the same as or opposite to the original pattern of the desired computed hologram.

In one embodiment, the photoresist is exposed by using a mask with a predetermined pattern or directly using a laser direct writing apparatus, and then a developing process is performed.

In one embodiment, the photoresist 4 is exposed by ultraviolet light.

Step 130: and etching the developed auxiliary film layer 3 by adopting preset gas, and stopping etching after continuously etching for a preset time period when the etching reaches the substrate 2 to generate the calculation hologram.

In the above steps, as shown in fig. 7, the material of the substrate 2 is different from the material of the auxiliary film 3, so that the etching rate of the predetermined gas on the substrate 2 is different from the etching rate on the auxiliary film 3, i.e. the etching difficulty is different. And because the gas concentration at each position is different and the etching rate is also different, the situation that the etching rate is also different at different positions of the substrate 2 inevitably occurs, so that when the etching reaches the substrate 2, the etching is continued for 3s-5s, each position needing to be etched is fully etched, and the etching uniformity is further improved.

In one embodiment, the auxiliary film 3 may be etched by a dry etching method, such as RIE (reactive ion etching) or ICP (inductively coupled plasma etching).

In an embodiment, the etching rate of the auxiliary film 3 by the predetermined gas may be determined in advance, for example, the etching may be performed on an experimental board with a known thickness, which is the same as the material of the auxiliary film 3, by using the predetermined gas, and the time required for the predetermined gas to etch the experimental board with the known thickness is recorded, so as to obtain the etching rate of the auxiliary film 3 by the predetermined gas. When the phase type calculation hologram is manufactured, the thickness of the auxiliary film layer 3 plated on the substrate 2 can be known, and the speed of the preset gas etching the auxiliary film layer 3 can be known, so that the time for the preset gas etching the complete auxiliary film layer 3 can be calculated, the etching can be stopped in time, the non-uniform etching depth can be prevented, and the calculation hologram with small etching error can be generated.

In an embodiment, the material of the auxiliary film 3 may be quartz, the thickness of the auxiliary film 3 may be 300nm-600nm, and SiO in the quartz₂The content of (silicon dioxide) is more than 99%.

In one embodiment, the substrate 2 may be made of glassSiO in BK7 and BK7 as raw materials₂The content range of (silicon dioxide) is 65% -73%.

In one embodiment, the predetermined gas is CHF₃(trifluoromethane) and/or CF₄(carbon tetrafluoride) and O₂And (3) mixing.

In practical scenarios, the preset gas is for SiO₂(silicon dioxide) etching, SiO₂The higher the (silicon dioxide) content, the faster the etching rate, the SiO of the substrate 2 material₂The content of (silicon dioxide) is obviously lower than that of SiO of the material of the auxiliary film layer 3₂(silicon dioxide) content, so that the etching rate is reduced once the etching process reaches the substrate 2 material layer, and therefore the etching rate of the predetermined gas on the substrate 2 is greater than that of the predetermined gas on the auxiliary film layer 3.

In one embodiment, the etching rate of the predetermined gas on the substrate 2 is less than 10nm/s, and the etching rate of the predetermined gas on the auxiliary film 3 is greater than 40 nm/s.

Step 140: and removing the residual photoresist on the auxiliary film layer.

In this step, the structure after removing the photoresist is as shown in fig. 8, the method for removing the residual photoresist may be dry photoresist removal, which is to remove the photoresist by using plasma. For example, using oxygen plasma, the photoresist on the auxiliary film layer is chemically reacted in the oxygen plasma to generate gaseous CO₂，CO₂And H₂The O can be pumped away by a vacuum system to complete the photoresist stripping process.

As shown in fig. 8, a compensator 1 obtained by the above method for the embodiment of the present application, wherein the generated compensator 1 includes: the film comprises a substrate 2, an auxiliary film layer 3 and photoresist 4, wherein the auxiliary film layer 3 and the photoresist 4 are arranged on the surface of the substrate 2.

In an actual scene, if the substrate 2 is directly etched by using an ion etching method in the process of generating the compensator 1, due to different ion concentrations in different areas in an etching cavity and different other etching parameters, the etching rates are different, so that the etching depths in different areas are not uniform, and the wavefront accuracy of the final compensator 1 is affected by the depth uniformity error. Therefore, in the present application, before the substrate 2 is etched, the substrate 2 is first coated, so that the coating precision can be controlled within 1%, and the thickness uniformity of the auxiliary film layer 3 is better. By selecting the auxiliary film layer 3 which is made of a material different from that of the substrate 2 and is easier to etch, and utilizing the characteristic that the preset gas etches different materials at different rates, the etching depth of the compensator 1 is controllable, and once the etching process reaches the substrate 2 layer, the etching rate can be reduced, so that the problem that the wavefront accuracy of the calculated hologram is influenced due to different etching rates caused by different ion concentrations in different regions in an etching cavity and different other etching parameters is solved.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.