CN118276211A - Method for preparing inclined grating by multi-step etching and inclined grating - Google Patents
Method for preparing inclined grating by multi-step etching and inclined grating Download PDFInfo
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- CN118276211A CN118276211A CN202211740877.5A CN202211740877A CN118276211A CN 118276211 A CN118276211 A CN 118276211A CN 202211740877 A CN202211740877 A CN 202211740877A CN 118276211 A CN118276211 A CN 118276211A
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- 238000005530 etching Methods 0.000 title claims abstract description 309
- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000000758 substrate Substances 0.000 claims abstract description 152
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 5
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 abstract description 30
- 210000002381 plasma Anatomy 0.000 description 108
- 239000007789 gas Substances 0.000 description 46
- 101100269850 Caenorhabditis elegans mask-1 gene Proteins 0.000 description 10
- 238000010586 diagram Methods 0.000 description 10
- 230000003287 optical effect Effects 0.000 description 9
- 230000007935 neutral effect Effects 0.000 description 8
- 239000002184 metal Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000003190 augmentative effect Effects 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- XPDWGBQVDMORPB-UHFFFAOYSA-N Fluoroform Chemical compound FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1847—Manufacturing methods
- G02B5/1857—Manufacturing methods using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/124—Geodesic lenses or integrated gratings
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Abstract
The application provides a method for preparing an inclined grating by multi-step etching and the inclined grating, wherein the preparation method comprises the following steps: the method comprises the steps of firstly carrying out first-step etching on an etching substrate, then carrying out second-step etching, wherein the DC bias voltage in the second-step etching is smaller than that in the first-step etching, namely, the preparation method firstly carries out high-energy etching, and then carries out low-energy etching, so that in the process of preparing the inclined grating, the etching substrate is subjected to fine etching, and the inclined grating prepared by the preparation method is higher in height and better in parallelism.
Description
Technical Field
The application relates to the technical field of grating preparation, in particular to a method for preparing an inclined grating by multi-step etching and the inclined grating prepared by the preparation method.
Background
Augmented reality (Augmented Reality, abbreviated as AR) is a technological field which has been paid attention to in recent years, and an optical waveguide device is a comparatively distinctive optical component which meets the demands of AR glasses.
The inclined grating is an important optical element in the optical waveguide device, and the height of the inclined grating and the parallelism of the two side walls are very important parameters, which affect the working performance of the inclined grating.
However, the parallelism of the prepared inclined grating cannot be guaranteed by the current preparation method, and even the situation that obvious turning or bifurcation exists on the side wall of the prepared inclined grating can occur.
Disclosure of Invention
In view of the above, the application provides a method for preparing an inclined grating by multi-step etching and the inclined grating, and the scheme is as follows:
a method of preparing a tilted grating by multi-step etching, the method comprising: providing an etching substrate, and placing the etching substrate in an etching chamber;
introducing etching gas into a discharge chamber, wherein the discharge chamber comprises a radio frequency power supply, the voltage of the radio frequency power supply is set to be a first direct current bias voltage, a first direct current signal is output, and the etching gas is ionized by using the first direct current signal to form first plasma;
performing first-step etching on the etched substrate by using the first plasma;
Setting the voltage of the radio frequency power supply as a second direct current bias voltage after the first step of etching, outputting a second direct current signal, and ionizing the etching gas by using the second direct current signal to form second plasma;
Performing second-step etching on the etched substrate by using the second plasma to form an inclined grating;
the voltage value of the second direct current bias voltage is smaller than that of the first direct current bias voltage.
Optionally, the preparation method further comprises:
Setting the voltage of the radio frequency power supply as a third direct current bias voltage after the second step of etching, outputting a third direct current signal, and ionizing the etching gas by using the third direct current signal to form third plasma;
Performing third etching on the etched substrate by using the third plasma to form an inclined grating;
the voltage value of the third direct current bias voltage is smaller than that of the second direct current bias voltage.
Optionally, the discharge chamber further comprises a bias power supply for outputting a bias signal; the first step of etching the etching substrate by using the first plasma comprises the following steps:
setting the voltage of the bias power supply as a first bias voltage, and outputting a first bias signal;
Controlling the first plasma to move by utilizing the first bias signal, leading the first plasma into the etching chamber, enabling the first plasma to be in contact with the etching substrate, and carrying out first-step etching on the etching substrate;
performing a second etching on the etched substrate by using the second plasma comprises:
setting the voltage of the bias power supply as a second bias voltage, and outputting a second bias voltage signal;
controlling the second plasma to move by utilizing the second bias signal, leading the second plasma into the etching chamber, enabling the second plasma to be in contact with the etching substrate, and carrying out second-step etching on the etching substrate;
The third step of etching the etching substrate by using the third plasma comprises the following steps:
setting the voltage of the bias power supply as a third bias voltage, and outputting a third bias voltage signal;
Controlling the third plasma to move by utilizing the third bias voltage signal, leading the third plasma into the etching chamber, enabling the third plasma to contact the etching substrate, and carrying out third etching on the etching substrate;
The voltage values of the first bias voltage, the second bias voltage and the third bias voltage are sequentially reduced; the second beam is not larger than the first beam, the third beam is smaller than the second beam, wherein the first beam is the current value of the current formed by the movement of the first plasma, the second beam is the current value of the current formed by the movement of the second plasma, and the third beam is the current value of the current formed by the movement of the third plasma.
Optionally, the moving direction of the first plasma, the moving direction of the second plasma and the moving direction of the third plasma have a first included angle with the surface of the etching substrate, and the value range of the first included angle is 0-80 degrees, and the left end point value is not included.
Optionally, the value range of the first direct current bias voltage is 500V-1200V; the value range of the second direct current bias voltage is 100V-400V; the third direct current bias voltage is 0.3-0.9 times of the second direct current bias voltage; the first bias voltage is 20% of the first dc bias voltage; the second bias voltage is 20% of the second DC bias voltage.
Optionally, the third dc bias voltage is greater than or equal to 200V, and the third bias voltage is 20% of the third dc bias voltage.
Optionally, the third dc bias voltage is between 100V and 200V, and the third bias voltage is equal to the third dc bias voltage.
Optionally, the third dc bias voltage is between 50V and 100V, and the sum of the third bias voltage and the third dc bias voltage is equal to 200V.
Optionally, if the thickness of the etched substrate is greater than or equal to 400nm, the preparation method further includes: performing a third step of etching on the etched substrate for a plurality of times;
And when the etching substrate is subjected to a plurality of third steps of etching, the third direct current bias voltage is gradually reduced.
Optionally, the etching gas is fluorocarbon gas, and the gas flow rate of the etching gas ranges from 10sccm to 200sccm.
Optionally, the material of the etching substrate is SiO 2, and the thickness of the etching substrate ranges from 50nm to 3000nm.
A tilted grating produced by the method according to any one of the above embodiments, the tilted grating comprising:
a substrate;
The substructures are positioned on the surface of the substrate and are sequentially arranged along the first direction, and the substructures are mutually parallel;
The substructure is provided with a first inclined edge and a second inclined edge which are opposite, an included angle between the first inclined edge and the second direction is a second included angle, an included angle between the second inclined edge and the second direction is a third included angle, and the difference between the second included angle and the third included angle is not more than 4 degrees;
The first direction is parallel to the substrate surface and the second direction is perpendicular to the substrate surface.
Optionally, in the second direction, the length of the substructure has a value ranging from 100nm to 3000nm.
Optionally, the distance between two adjacent substructures in the plurality of substructures is 100 nm-1500 nm; in the second direction, the length of the substructure is in the range of 20nm to 1200nm.
Compared with the prior art, the technical scheme of the application has the beneficial effects that:
The application provides a method for preparing an inclined grating by multi-step etching and the inclined grating, wherein the preparation method comprises the following steps: the method comprises the steps of firstly carrying out first-step etching on an etching substrate, then carrying out second-step etching, wherein the DC bias voltage in the second-step etching is smaller than that in the first-step etching, namely, the preparation method firstly carries out high-energy etching, and then carries out low-energy etching, so that in the process of preparing the inclined grating, the etching substrate is subjected to fine etching, and the inclined grating prepared by the preparation method is higher in height and better in parallelism.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the drawings required for the description of the embodiments or the prior art will be briefly described below, and it is apparent that the drawings in the following description are only embodiments of the present application, and other drawings may be obtained according to the provided drawings without inventive effort to those skilled in the art.
The structures, proportions, sizes, etc. shown in the drawings are shown only in connection with the present disclosure, and are not intended to limit the scope of the application, since any modification, variation in proportions, or adjustment of the size, etc. of the structures, proportions, etc. should be considered as falling within the spirit and scope of the application, without affecting the effect or achievement of the objective.
FIG. 1 is a schematic diagram of a tilted grating produced by a prior art method of production;
FIG. 2 is a schematic diagram of another tilted grating produced by a prior art production process;
FIG. 3 is a flow chart of a method for preparing an inclined grating by multi-step etching according to the present application;
FIG. 4 is a schematic diagram of a structure of an etching sample consisting of a substrate base, an etching base and a hard mask;
FIG. 5 is a schematic diagram of a tilted grating structure according to a first embodiment;
FIG. 6 is a schematic diagram of a tilted grating structure according to a second embodiment;
FIG. 7 is a schematic diagram of a tilted grating structure according to a first embodiment of the present application;
FIG. 8 is a schematic diagram of a tilted grating structure according to a second embodiment of the present application;
FIG. 9 is a schematic diagram of another structure of an etching sample consisting of a substrate base, an etching base and a hard mask;
FIG. 10 is a schematic diagram of a tilted grating structure according to a third embodiment of the present application;
Fig. 11 is a schematic structural diagram of an oblique grating according to an embodiment of the present application.
Detailed Description
Embodiments of the present application will now be described more fully hereinafter with reference to the accompanying drawings, in which it is shown, however, that the embodiments shown are merely exemplary, and not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description.
For AR technology, optical waveguide technology is a very important ring, which plays a critical role in AR implementation, and tilted gratings are one of the very important optical elements in optical waveguide instruments. Therefore, for AR technology, a tilted grating is also one of important elements affecting the effect achieved.
In general, the conditions of use of the tilted grating in an optical waveguide instrument are fixed, and thus, to obtain a desired diffraction effect, it is necessary to achieve this by optimizing the structural parameters of the tilted grating. For the inclined grating, the most important parameters include the grating height and the angle difference of the side walls at two sides of the grating, namely the parallelism of the two side walls, wherein the higher grating height can increase the diffraction area, the good parallelism of the side walls of the grating can improve the diffraction efficiency, and the matching effect of the coupling-in end and the coupling-out end of the optical path is good.
At present, most inclined gratings are produced in a large scale by adopting a nanoimprint working die, and the method has the advantages that the same master grating can be used for producing the replica gratings with the same parameters in a large scale, and the cost is low. Reactive ion beam etching systems are now commonly used in the industry to produce tilted gratings, which are obtained with a certain tilt and height by varying the angle, energy and etching time of the ion beam. However, the currently used method generally cannot guarantee the parallelism of the side wall of the SiO2 inclined grating, as shown in fig. 1; even a significant inflection or bifurcation in the sidewall occurs as shown in fig. 2.
Based on this, the present application provides a method for preparing an inclined grating by multi-step etching, as shown in fig. 3, the preparation method comprises:
S1: providing an etching substrate, and placing the etching substrate in an etching chamber;
S2: introducing etching gas into a discharge chamber, wherein the discharge chamber comprises a radio frequency power supply, the voltage of the radio frequency power supply is set to be a first direct current bias voltage, a first direct current signal is output, and the etching gas is ionized by using the first direct current signal to form first plasma;
S3: performing first-step etching on the etched substrate by using the first plasma;
S4: setting the voltage of the radio frequency power supply as a second direct current bias voltage after the first step of etching, outputting a second direct current signal, and ionizing the etching gas by using the second direct current signal to form second plasma;
S5: performing second-step etching on the etched substrate by using the second plasma to form an inclined grating;
The voltage value of the second direct current bias voltage is smaller than that of the first direct current bias voltage. In step S1, a hard mask is further disposed on the surface of the etching substrate before the etching substrate is placed in the etching chamber, and the etching gas etches the etching substrate along the image shape of the hard mask. It should be noted that, the formation of plasma is related to the power of the rf power supply, and the power of the rf power supply is related to the dc bias voltage of the rf power supply, so that different plasmas can be formed by setting different dc voltages in different etching steps to perform etching with different energies.
Specifically, in the embodiment of the application, the preparation method comprises the following steps: setting the voltage of a radio frequency power supply as a first direct current bias voltage, outputting a first direct current signal, ionizing etching gas to form first plasma, and performing first-step etching on an etched substrate by using the first plasma; and setting the voltage of the radio frequency power supply as a second direct current bias voltage, outputting a second direct current signal, ionizing etching gas to form second plasma, and performing second-step etching on the etched substrate by using the second plasma, wherein the voltage value of the second direct current bias voltage is smaller than that of the second direct current bias voltage. Therefore, the preparation method provided by the application adopts multi-step etching in the process of preparing the inclined grating, and the voltage value of the direct current bias voltage in the later step of etching is smaller than that in the former step of etching, namely, the direct current bias voltages in different etching steps in the preparation method are gradually reduced, namely, the preparation method firstly carries out high-energy etching step and then carries out low-energy etching step, so that the etched substrate is subjected to fine etching in the process of preparing the inclined grating, and the inclined grating prepared by the preparation method is higher in height and better in parallelism.
On the basis of the above embodiment, in one embodiment of the present application, the preparation method further includes:
S6: setting the voltage of the radio frequency power supply as a third direct current bias voltage after the second step of etching, outputting a third direct current signal, and ionizing the etching gas by using the third direct current signal to form third plasma;
S7: performing third etching on the etched substrate by using the third plasma;
the voltage value of the third direct current bias voltage is smaller than that of the second direct current bias voltage.
It should be noted that, when the height of the oblique grating to be manufactured is higher, when the thickness of the etching substrate is thicker, the depth of the etching substrate is also larger, so that in order to ensure the parallelism of the oblique grating and the height of the oblique grating when the thickness of the etching substrate is thicker, more steps of etching are needed to be performed on the etching substrate. Therefore, on the basis of the above embodiment, in one embodiment of the present application, according to the thickness of the etched substrate, the preparation method further includes a third step of etching, so as to perform fine etching on the etched substrate with a thicker thickness, and obtain the inclined grating with a higher height and a better parallelism.
On the basis of the above embodiments, in one embodiment of the present application, the discharge chamber further includes a bias power supply for outputting a bias signal; for step S3, performing a first step of etching the etched substrate using the first plasma includes:
S31: setting the voltage of the bias power supply as a first bias voltage, and outputting a first bias signal;
s32: controlling the first plasma to move by utilizing the first bias signal, leading the first plasma into the etching chamber, enabling the first plasma to be in contact with the etching substrate, and carrying out first-step etching on the etching substrate;
For step S5, performing a second etching on the etched substrate using the second plasma includes:
s51: setting the voltage of the bias power supply as a second bias voltage, and outputting a second bias voltage signal;
S52: controlling the second plasma to move by utilizing the second bias signal, leading the second plasma into the etching chamber, enabling the second plasma to be in contact with the etching substrate, and carrying out second-step etching on the etching substrate;
For step S7, performing a third etching on the etched substrate using the third plasma includes:
s71: setting the voltage of the bias power supply as a third bias voltage, and outputting a third bias voltage signal;
S72: controlling the third plasma to move by utilizing the third bias voltage signal, leading the third plasma into the etching chamber, enabling the third plasma to be in contact with the etching substrate, and carrying out third etching on the etching substrate;
Wherein the voltage values of the first bias voltage, the second bias voltage and the third bias voltage are sequentially reduced; the second beam is not larger than the first beam, the third beam is smaller than the second beam, wherein the first beam is the current value of the current formed by the movement of the first plasma, the second beam is the current value of the current formed by the movement of the second plasma, and the third beam is the current value of the current formed by the movement of the third plasma. It should be noted that, the plasma is a charged body, so that a bias signal drives the plasma to move to form a current, and the current value of the current can represent the flow of the plasma, so that the first beam, the second beam and the third beam represent the flow of the plasma in different etching steps respectively.
Optionally, the value range of the first beam is 100 mA-1200 mA, including the endpoint value; the value range of the second beam is 50 mA-500 mA, including the endpoint value; the value range of the third beam is 50 mA-500 mA, including the end point value, but the comparison of the application is not limited, and the application is specifically determined according to the situation.
On the basis of the above embodiment, in one embodiment of the present application, the preparation method further includes:
s8: and after the etching substrate is etched, taking out the etched substrate, and removing the hard mask on the surface of the etched substrate to finish the preparation of the inclined grating. Optionally, the hard mask is a metal mask, and the material of the hard mask may be one of Cr, mo, al, al 2O3, tiN, etc., but the present application is not limited thereto, and the material is specifically defined as the case may be.
On the basis of the above embodiment, in one embodiment of the present application, the moving direction of the first plasma, the moving direction of the second plasma, and the moving direction of the third plasma are the same or approximately the same, a first included angle is formed between the moving direction of the first plasma, the moving direction of the second plasma, and the moving direction of the third plasma and the surface of the etched substrate, and the value range of the first included angle is 0 ° to 80 °, excluding the left end value, so that when the first plasma, the second plasma, and the third plasma etch the etched substrate, the etching direction has a certain angle, and an inclined grating is formed.
Based on the above embodiments, in one embodiment of the present application, the value range of the first dc bias voltage is 500V to 1200V, including the end point value; the value range of the second direct current bias voltage is 100V-400V, including the endpoint value; the third DC bias voltage is 0.3-0.9 times of the second DC bias voltage, including the end point value; the first bias voltage is 20% of the first direct current bias voltage, namely the value range of the first bias voltage is 100V-240V, and the end point value is the value; the second bias voltage is 20% of the second DC bias voltage, namely the value range of the second bias voltage is 20V-80V, including the end point value.
On the basis of the above embodiment, in one embodiment of the present application, the third dc bias is greater than or equal to 200V, and the third bias is 20% of the third dc bias.
In another embodiment of the present application, the third dc bias voltage is between 100V and 200V, including a left end point value, and the third bias voltage is equal to the third dc bias voltage.
In yet another embodiment of the present application, the third dc bias voltage is between 50V and 100V, including a left end point value, and a sum of the third bias voltage and the third dc bias voltage is equal to 200V.
It should be noted that, according to the above known technique, when the thickness of the etched substrate is large, it is necessary to perform more etching steps on the etched substrate. Thus, in one embodiment of the present application, if the thickness of the etched substrate is greater than or equal to 400nm, the preparation method further comprises: performing multiple third-step etching on the etched substrate, namely repeating the multiple third-step etching; and when the etching substrate is subjected to a plurality of third steps of etching, the third direct current bias voltage is gradually reduced. And performing multiple third-step etching on the etching substrate, wherein the third direct current bias voltage is gradually reduced, specifically, when performing multiple third-step etching, the direct current bias voltage in the next third-step etching is smaller than the direct current bias voltage in the previous third-step etching, and the direct current bias voltage in the next third-step etching is 0.3-0.9 times of the direct current bias voltage in the previous third-step etching, but the attention is paid to that the minimum third direct current bias voltage cannot be lower than 50V so as to prevent the third direct current bias voltage from being too low and affecting the normal operation of etching work. In addition, when the third etching is repeated, the beam current of the plasma in the last etching is smaller than that in the previous etching.
Optionally, the thickness of the etched substrate is greater than or equal to 400nm, and when the etching substrate is etched for a plurality of third steps, the etching for the third step is repeated at most four times, but the application is not limited thereto, and the application is specifically determined according to the situation.
On the basis of any one of the above embodiments, in one embodiment of the present application, the etching gas is fluorocarbon gas; and the gas flow of the etching gas ranges from 10sccm to 200sccm, including the end point values, but the application is not limited thereto, and the application is particularly limited according to the situation.
Optionally, the etching gas is at least one of CH 2F2、CHF3、CF4、C2F6、C4F8, but the present application is not limited thereto, and the etching gas may be fluorocarbon gas other than the above gases, as the case may be.
Based on any one of the above embodiments, in one embodiment of the present application, the material of the etched substrate is SiO 2, and the thickness range is 50nm to 3000nm, including the end point value, so that the height of the prepared inclined grating can reach 300nm, and thus the inclined grating has a higher height and a larger diffraction area. In addition, the thickness of the hard mask is 10% -50% of the thickness of the etching substrate, including the end point value.
The preparation method provided by the application is described in detail below by way of comparative examples and examples of the application.
Comparative example one:
Placing an etching sample in an etching chamber, wherein as shown in fig. 4, the thickness of a hard mask 1 is 100nm, the pattern period is 200nm, the line width is 200nm, the thickness of an etching substrate 2 is 360nm, the thickness of a substrate 3 is 50nm, the etching substrate 2 is positioned on the surface of the substrate 3, and the substrate 3, the etching substrate 2 and the hard mask 1 are combined into the etching sample and placed in the etching chamber; the hard mask is a metal Cr mask, etching gas is CHF 3, the flow rate of the etching gas is set to be 24sccm, the voltage of a radio frequency power supply is set to be 600V, the voltage of a bias power supply is set to be 120V, the current formed by plasma is 160mA, the etching gas is introduced into a discharge chamber to form plasma, the movement of the plasma is controlled, the plasma passes through a grid mesh and is neutralized to be in electric neutrality, the plasma is in contact with the surface of an etching substrate, and the etching substrate is etched at an etching angle of 30 degrees for 500s; and then taking out the etched sample, and removing the hard mask at the top to form the inclined grating.
As shown in fig. 5, the height of the oblique grating formed by the method is 360nm, and as can be seen from fig. 5, the quality of the oblique grating is poor, the flatness of the left side wall of the oblique grating is poor, an obvious turning surface appears, the included angle between the upper part of the turning surface and the second direction is 36 degrees, and the included angle between the lower part of the turning surface and the second direction is 31 degrees; the right side wall of the grating has no turning surface and the included angle between the right side wall and the second direction is 27 degrees.
Comparative example two:
Placing an etching sample in an etching chamber, wherein as shown in fig. 4, the thickness of a hard mask 1 is 100nm, the pattern period is 200nm, the line width is 200nm, the thickness of an etching substrate 2 is 360nm, the thickness of a substrate 3 is 50nm, the etching substrate 2 is positioned on the surface of the substrate 3, and the substrate 3, the etching substrate 2 and the hard mask 1 are combined into the etching sample and placed in the etching chamber; the hard mask is a metal Cr mask, etching gas is CHF 3, the flow rate of the etching gas is set to be 24sccm, the voltage of a radio frequency power supply is set to be 300V, the voltage of a bias power supply is set to be 80V, the current formed by plasma is 160mA, the etching gas is introduced into a discharge chamber to form plasma, the movement of the plasma is controlled, the plasma passes through a grid mesh and is neutralized to be neutral, the plasma is in contact with the surface of an etching substrate, and the etching angle is 30 degrees, and the etching time is 1200s; and then taking out the etched sample, and removing the hard mask at the top to form the inclined grating.
As shown in fig. 6, the height of the oblique grating formed by the method is 360nm, turning surfaces are not formed on two side walls, the included angles between the two side walls and the second direction are 33 degrees and 23 degrees respectively, and the angle difference is 10 degrees.
According to the first and second comparative examples, the sidewall flatness of the formed inclined grating is better, but the parallelism is worse when the voltage of the rf power source is lower.
In the first embodiment of the application:
Placing an etching sample in an etching chamber, wherein as shown in fig. 4, the thickness of a hard mask 1 is 100nm, the pattern period is 200nm, the line width is 200nm, the thickness of an etching substrate 2 is 360nm, the thickness of a substrate 3 is 50nm, the etching substrate 2 is positioned on the surface of the substrate 3, and the substrate 3, the etching substrate 2 and the hard mask 1 are combined into the etching sample and placed in the etching chamber; the hard mask is a metal Cr mask and the etching gas is CHF 3.
Performing first-step etching, namely setting the flow of etching gas to be 24sccm, setting the first direct-current bias to be 600V, setting the first bias to be 120V, setting the first beam to be 160mA, introducing etching gas into a discharge chamber to form first plasma, controlling the movement of the plasma to enable the plasma to pass through a grid mesh and neutralize the plasma to be neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing first-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 250s; performing second-step etching, namely setting the flow of etching gas to be 24sccm, setting the second direct-current bias to be 300V, setting the second bias to be 60V, setting the first beam current to be 160mA, introducing etching gas into a discharge chamber to form first plasma, controlling the movement of the plasma, enabling the plasma to pass through a grid mesh and neutralize to be electrically neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing first-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 600s; and then taking out the etched sample, and removing the hard mask at the top to form the inclined grating.
As shown in FIG. 7, the height of the inclined grating formed by the method is 360nm, turning surfaces are not formed on two side walls, and the flatness is good. And the included angles between the two side walls and the second direction are 31 degrees and 27 degrees respectively, the angle difference is 4 degrees, and the parallelism is good.
Compared with the first and second embodiments, the first and second embodiments of the present application have the advantages that the etching substrate is etched twice, the voltage of the radio frequency power supply and the voltage of the bias power supply are gradually reduced in the two etches, and the flatness and parallelism of the inclined grating obtained in the first embodiment of the present application are improved, so that the preparation method provided by the present application uses higher energy to perform the first etching step, and then uses lower energy to perform the second etching step, so that the flatness and parallelism of the inclined grating obtained in the first embodiment of the present application are improved, and the preparation method provided by the present application is helpful to obtain the inclined grating with good diffraction performance.
In the second embodiment of the application:
Placing an etching sample in an etching chamber, wherein as shown in fig. 4, the thickness of a hard mask 1 is 100nm, the pattern period is 200nm, the line width is 200nm, the thickness of an etching substrate 2 is 360nm, the thickness of a substrate 3 is 50nm, the etching substrate 2 is positioned on the surface of the substrate 3, and the substrate 3, the etching substrate 2 and the hard mask 1 are combined into the etching sample and placed in the etching chamber; the hard mask is a metal Cr mask and the etching gas is CHF 3.
Performing first-step etching, namely setting the flow of etching gas to be 24sccm, setting the first direct-current bias to be 600V, setting the first bias to be 120V, setting the first beam to be 160mA, introducing etching gas into a discharge chamber to form first plasma, controlling the movement of the plasma to enable the plasma to pass through a grid mesh and neutralize the plasma to be neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing first-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 250s; performing second-step etching, namely setting the flow of etching gas to be 24sccm, setting the second direct current bias to be 300V, setting the second bias to be 60V, setting the second beam to be 320mA, introducing etching gas into a discharge chamber to form second plasma, controlling the movement of the plasma, enabling the plasma to pass through a grid mesh and neutralize to be electrically neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing second-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 350s; and then taking out the etched sample, and removing the hard mask at the top to form the inclined grating.
As shown in FIG. 8, the height of the inclined grating formed by the method is 360nm, turning surfaces are not formed on two side walls, and the flatness is good. And the included angles between the two side walls and the second direction are respectively 32 degrees and 26 degrees, and the angle difference is 6 degrees.
Compared with the first embodiment of the application, when the low-energy etching is performed, if the beam current of the plasma in the low-energy etching step is larger than that of the plasma in the high-energy etching step, the parallelism of the prepared inclined grating is reduced, so that the second beam current in the preparation method provided by the application is not larger than that of the first beam current.
The third embodiment of the application:
Placing an etching sample in an etching chamber, wherein as shown in fig. 9, the thickness of a hard mask 1 is 100nm, the pattern period is 200nm, the line width is 200nm, the thickness of an etching substrate 2 is 400nm, the thickness of a substrate 3 is 50nm, the etching substrate 2 is positioned on the surface of the substrate 3, and the substrate 3, the etching substrate 2 and the hard mask 1 are combined into the etching sample and placed in the etching chamber; the hard mask is a metal Cr mask and the etching gas is CHF 3.
Performing first-step etching, namely setting the flow of etching gas to be 24sccm, setting the first direct-current bias to be 600V, setting the first bias to be 120V, setting the first beam to be 160mA, introducing etching gas into a discharge chamber to form first plasma, controlling the movement of the plasma to enable the plasma to pass through a grid mesh and neutralize the plasma to be neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing first-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 250s; performing second-step etching, namely setting the flow of etching gas to be 24sccm, setting the second direct current bias to be 300V, setting the second bias to be 60V, setting the second beam to be 160mA, introducing etching gas into a discharge chamber to form second plasma, controlling the movement of the plasma, enabling the plasma to pass through a grid mesh and neutralize to be electrically neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing second-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 600s; performing third-step etching, namely setting the flow of etching gas to be 24sccm, setting the third direct current bias to be 100V, setting the third bias to be 60V, setting the third beam to be 160mA, introducing etching gas into a discharge chamber to form third plasma, controlling the movement of the plasma, enabling the plasma to pass through a grid mesh and neutralize to be electrically neutral, enabling the plasma to be in contact with the surface of an etching substrate, and performing third-step etching on the etching substrate, wherein the etching angle is 30 degrees, and the etching time is 500s; then taking out the etching sample, removing the hard mask at the top, and forming an inclined grating;
As shown in FIG. 10, the height of the inclined grating formed by the method is 400nm, turning surfaces do not appear on two side walls, and the flatness is good. And the included angles between the two side walls and the second direction are 31 degrees and 27 degrees respectively, and the angle difference is 4 degrees.
Compared with the first embodiment of the application, when the thickness of the etched substrate is thicker, in order to ensure the etching depth, namely the height of the manufactured inclined grating, more times of etching are needed to be performed on the etched substrate, so that the preparation method provided by the application needs to repeat the third etching step for a plurality of times when the thickness of the etched substrate is larger than 400 nm.
Correspondingly, the application also provides a tilted grating manufactured by the tilted grating manufacturing method according to any of the embodiments, as shown in fig. 11, which includes:
A substrate 4;
A plurality of substructures 5 arranged on the surface of the substrate in sequence along a first direction, wherein the substructures 5 are parallel to each other;
the substructure 5 has a first oblique side 51 and a second oblique side 52 which are opposite, a second included angle A1 is formed between the first oblique side 51 and the second direction, a third included angle A2 is formed between the second oblique side 52 and the second direction, and a difference between the first included angle A1 and the second included angle A2 is not greater than 4 °;
The first direction is parallel to the surface of the substrate 4 and the second direction is perpendicular to the surface of the substrate 4.
Specifically, in the embodiment of the present application, a second included angle and a third included angle are formed between the first oblique side and the second oblique side of the substructure of the inclined grating and the second direction, and the difference between the second included angle and the third included angle is not greater than 4 °, i.e., the angle difference between the two sidewalls of the inclined grating is not greater than 4 °, so as to indicate that the parallelism of the inclined grating is better and the diffraction efficiency is higher.
On the basis of the above embodiment, in one embodiment of the present application, as shown in fig. 10, in the second direction, the length L1 of the substructure 5 has a value ranging from 100nm to 400nm, including an end point value, that is, the height of the substructure has a value ranging from 100nm to 400nm, including an end point value, that is, the height of the tilted grating has a value ranging from 100nm to 3000nm, including an end point value, so that the height of the tilted grating can reach up to 3um, thereby making the height of the tilted grating higher and the diffraction area larger.
Based on the above embodiments, in one embodiment of the present application, as shown in fig. 10, the range of values of the distance L2 between two adjacent substructures in the plurality of substructures is 100nm to 1500nm, including the end point value, that is, the range of values of the pattern period of the oblique grating is 100nm to 1500nm, including the end point value; in the first direction, the length L3 of the substructure is in a range of 20nm to 1200nm inclusive, i.e., the line width of the tilted grating is in a range of 20nm to 1200nm inclusive.
In summary, the inclined grating provided by the application has higher height and higher parallelism, and thus the inclined grating provided by the application has excellent diffraction performance.
In summary, the present application provides a method for preparing an inclined grating by multi-step etching and the inclined grating, and the preparation method includes: the method comprises the steps of firstly carrying out first-step etching on an etching substrate, then carrying out second-step etching, wherein the DC bias voltage in the second-step etching is smaller than that in the first-step etching, namely, the preparation method firstly carries out high-energy etching, and then carries out low-energy etching, so that in the process of preparing the inclined grating, the etching substrate is subjected to fine etching, and the inclined grating prepared by the preparation method is higher in height and better in parallelism.
In the present specification, each embodiment is described in a progressive manner, or a parallel manner, or a combination of progressive and parallel manners, and each embodiment is mainly described as different from other embodiments, and the same similar areas between the embodiments are referred to each other. For the device disclosed in the embodiment, since the device corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method area.
It should be noted that, in the description of the present application, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in an article or device comprising the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (14)
1. A method for preparing an inclined grating by multi-step etching, which is characterized by comprising the following steps:
providing an etching substrate, and placing the etching substrate in an etching chamber;
introducing etching gas into a discharge chamber, wherein the discharge chamber comprises a radio frequency power supply, the voltage of the radio frequency power supply is set to be a first direct current bias voltage, a first direct current signal is output, and the etching gas is ionized by using the first direct current signal to form first plasma;
performing first-step etching on the etched substrate by using the first plasma;
Setting the voltage of the radio frequency power supply as a second direct current bias voltage after the first step of etching, outputting a second direct current signal, and ionizing the etching gas by using the second direct current signal to form second plasma;
Performing second-step etching on the etched substrate by using the second plasma to form an inclined grating;
the voltage value of the second direct current bias voltage is smaller than that of the first direct current bias voltage.
2. The method of manufacturing a tilted grating of claim 1, further comprising:
Setting the voltage of the radio frequency power supply as a third direct current bias voltage after the second step of etching, outputting a third direct current signal, and ionizing the etching gas by using the third direct current signal to form third plasma;
Performing third etching on the etched substrate by using the third plasma to form an inclined grating;
the voltage value of the third direct current bias voltage is smaller than that of the second direct current bias voltage.
3. The method of preparing a tilted grating of claim 2, wherein the discharge chamber further comprises a bias power supply for outputting a bias signal; the first step of etching the etching substrate by using the first plasma comprises the following steps:
setting the voltage of the bias power supply as a first bias voltage, and outputting a first bias signal;
Controlling the first plasma to move by utilizing the first bias signal, leading the first plasma into the etching chamber, enabling the first plasma to be in contact with the etching substrate, and carrying out first-step etching on the etching substrate;
performing a second etching on the etched substrate by using the second plasma comprises:
setting the voltage of the bias power supply as a second bias voltage, and outputting a second bias voltage signal;
controlling the second plasma to move by utilizing the second bias signal, leading the second plasma into the etching chamber, enabling the second plasma to be in contact with the etching substrate, and carrying out second-step etching on the etching substrate;
The third step of etching the etching substrate by using the third plasma comprises the following steps:
setting the voltage of the bias power supply as a third bias voltage, and outputting a third bias voltage signal;
Controlling the third plasma to move by utilizing the third bias voltage signal, leading the third plasma into the etching chamber, enabling the third plasma to contact the etching substrate, and carrying out third etching on the etching substrate;
The voltage values of the first bias voltage, the second bias voltage and the third bias voltage are sequentially reduced; the second beam is not larger than the first beam, the third beam is smaller than the second beam, wherein the first beam is the current value of the current formed by the first plasma motion, the second beam is the current value of the current formed by the second plasma motion, and the third beam is the current value of the current formed by the third plasma motion.
4. The method of manufacturing a tilted grating as recited in claim 3, wherein the direction of movement of the first plasma, the direction of movement of the second plasma, and the direction of movement of the third plasma have a first angle with the surface of the etched substrate, and the first angle has a value in a range of 0 ° to 80 °, excluding a left end point value.
5. A method of producing a tilted grating as defined in claim 3, wherein the first dc bias voltage has a value in the range of 500V to 1200V; the value range of the second direct current bias voltage is 100V-400V; the third direct current bias voltage is 0.3-0.9 times of the second direct current bias voltage; the first bias voltage is 20% of the first dc bias voltage; the second bias voltage is 20% of the second DC bias voltage.
6. The method of manufacturing a tilted grating of claim 5, wherein the third dc bias voltage is greater than or equal to 200V, and the third bias voltage is 20% of the third dc bias voltage.
7. The method of manufacturing a tilted grating of claim 5, wherein the third dc bias voltage is between 100V and 200V, the third bias voltage being equal to the third dc bias voltage.
8. The method of manufacturing a tilted grating of claim 5, wherein the third dc bias voltage is between 50V and 100V, and the sum of the third bias voltage and the third dc bias voltage is equal to 200V.
9. The method of manufacturing a tilted grating of claim 2, wherein if the etched substrate has a thickness of 400nm or greater, the method further comprises: performing a third step of etching on the etched substrate for a plurality of times;
And when the etching substrate is subjected to a plurality of third steps of etching, the third direct current bias voltage is gradually reduced.
10. The method of manufacturing a tilted grating of claim 1, wherein the etching gas is a fluorocarbon gas and the flow rate of the etching gas has a value ranging from 10sccm to 200sccm.
11. The method of manufacturing a tilted grating according to claim 1, wherein the material of the etched substrate is SiO 2, and the thickness of the etched substrate has a value ranging from 50nm to 3000nm.
12. A tilted grating produced by the method of any one of claims 1-11, the tilted grating comprising:
a substrate;
a plurality of substructures which are sequentially arranged along a first direction and are positioned on the surface of the substrate;
The substructure is provided with a first inclined edge and a second inclined edge which are opposite, an included angle between the first inclined edge and the second direction is a second included angle, an included angle between the second inclined edge and the second direction is a third included angle, and the difference between the second included angle and the third included angle is not more than 4 degrees;
The first direction is parallel to the substrate surface and the second direction is perpendicular to the substrate surface.
13. The tilted grating of claim 12, wherein the length of the substructure in the second direction is in the range of 100nm to 3000nm.
14. The tilted grating of claim 12, wherein a distance between two adjacent substructures of the plurality of substructures ranges from 100nm to 1500nm; in the first direction, the length of the substructure is in the range of 20nm to 1200nm.
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