CN114446745A - Hole die and method for adjusting ion etching uniformity - Google Patents

Abstract

The invention discloses a nut block for adjusting the uniformity of ion etching, which comprises a cap part and a rod part, wherein one end of the rod part is fixedly connected with the cap part, the side surface of the rod part is provided with a notch, the rod part is connected to the position, deviating from the center of the cap part, on the cap part, the width of the notch is equal to the thickness of a metal sheet of a grid mesh, the rod part is provided with a plurality of notches, the notches are uniformly distributed along the length direction of the rod part, and the distance between every two adjacent notches is equal to the distance between every two adjacent metal sheets of the grid mesh.

Description

Hole die and method for adjusting ion etching uniformity

Technical Field

The invention belongs to the technical field of ion sputtering, and particularly relates to a porous block and a method for adjusting ion etching uniformity.

Background

The grid ion source generally generates an argon (Ar) plasma using an Inductive Coupling (ICP) using a radio frequency power supply; accelerating argon plasma through a metal grid mesh with different voltages, and forming a plasma beam with high energy and parallel as much as possible; guiding the plasma beam to bombard the surface of the silicon substrate, and etching substances on the surface of the silicon substrate to clean the surface of the silicon substrate; or various micro and nano structures are processed and molded on the silicon substrate.

In conventional grid ion sources, the grid is made up of a structure of a number of honeycomb shaped holes. The size and the layout of the holes are adjusted, on one hand, the amount of plasma which passes through the holes and is in different areas can be adjusted, so that the etching rate in different areas can be adjusted; on the other hand, the running tracks of the plasmas can be more parallel, and the uniformity of the etching rate can be improved. However, there are limitations to using a grid. The method is mainly characterized in that an ion source generated by Inductive Coupling (ICP) is influenced by the nonuniformity of the magnetic field intensity generated by a coil, the diffusion of etching gas, the equipment design, the part processing and mounting precision and the like, so that the density distribution of the generated plasma is not very uniform; meanwhile, in the etching process, the RF power, voltage, process gas type, gas pressure, flow and the like of the ion source are all different in different processes.

Therefore, in the process of tuning the etching process, the optimization of the process parameters cannot fully meet the process performance requirements (usually, the uniformity of the etching rate) in many cases. At this point, the grid structure is redesigned, fabricated, and retested. Therefore, the process optimization period is long, and the service time and the production capacity of equipment are seriously reduced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the ion source grid mesh which can be conveniently inserted into the holes of the metal sheet on the grid mesh to form a stable structure with the grid mesh so as to conveniently and rapidly adjust the local ion concentration of the ion source grid mesh and rapidly optimize the etching uniformity.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides an adjust hole butyl of ion etching homogeneity, includes cap portion and pole portion, the one end and the cap portion fixed connection of pole portion, the side of pole portion is provided with the notch.

The stem portion is further attached to the cap at a position offset from the center of the cap.

Further the width of the slot is equal to the thickness of the metal sheet of the grid.

Further the cap is sized to cover the apertures of one mesh or the apertures of adjacent meshes.

Further the cap is circular in cross-section.

Further have a plurality of notches on the pole portion, a plurality of notches are along the length direction evenly distributed of pole portion, and the interval of two adjacent notches equals the interval of two adjacent sheetmetals of bars net.

The cap part and the rod part are further made of ceramic or quartz.

A method for adjusting ion etching uniformity comprises the following steps:

s1: etching the wafer by adopting an ion source grid mesh to obtain ion etching thickness or rate distribution data; s2: preparing an etching thickness or rate T ═ f (R/R) graph;

s3: judging whether the etching uniformity requirement is met according to the T-f (R/R) diagram;

s4: if the requirement of etching uniformity is met, the step S5 is carried out; if the requirement of etching uniformity is not met, inserting a plurality of holes at the positions of the corresponding ion source grids at the positions with higher etching thickness according to a T ═ f (R/R) diagram, and then returning to the step S1;

s5: and finishing the adjustment.

Compared with the prior art, the invention has the beneficial effects that: can be conveniently inserted into the metal sheet holes of the grid mesh and forms a stable structure with the metal sheet holes according to the self gravity and the geometric shape. Therefore, the local ion concentration of the ion source grid can be conveniently and rapidly adjusted, the etching uniformity is further rapidly optimized, and the use efficiency and the capacity of equipment are improved.

Drawings

FIG. 1 is a schematic diagram of a grid explosion;

FIG. 2 is a schematic view of a memorable metal sheet;

FIG. 3 is a diagram of a first embodiment of a hole die for adjusting ion etching uniformity according to the present invention;

FIG. 4 is a schematic diagram of a second embodiment of a hole die for adjusting ion etching uniformity according to the present invention;

FIG. 5 is a flow chart of a method of adjusting ion etch uniformity according to the present invention;

FIGS. 6-9 show examples of ion etching uniformity control using a method of adjusting the uniformity of ion etching using a porous die.

Reference numerals: 1. a cap portion; 2. a rod portion; 21. a notch; 3. a metal sheet; 31. a hole; 4. isolating the ceramic.

Detailed Description

Embodiments of the present invention are further described with reference to fig. 1 to 9.

In the description of the present invention, it should be noted that, for the terms of orientation, such as "central", "lateral (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate that the orientation and positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific scope of the present invention.

Furthermore, if the terms "first" and "second" are used for descriptive purposes only, they are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. Thus, a definition of "a first" or "a second" feature may explicitly or implicitly include one or more of the features, and in the description of the invention, "a number" or "a number" means two or more unless explicitly specified otherwise.

The ion source mainly comprises a grid, a Radio Frequency (RF) power supply coil, a quartz cavity, an airflow guide structure and the like. Wherein the content of the first and second substances,

1. the gas flow guide structure introduces etching gas such as argon and enables the etching gas to be uniformly distributed in the vacuum quartz cavity;

2. a Radio Frequency (RF) power supply that provides energy to ionize a gas in a vacuum quartz chamber;

3. the grid mesh is usually composed of 3-5 metal sheets 3 which have the same structure, are insulated from each other and are connected with different voltages. The ion flow is accelerated by the grids with different electric fields, and the ion flow passes through the grids to form approximately parallel plasma beams with high energy. Typically, a substrate is placed on a substrate table. The substrate table may be rotated to assist in improving the uniformity of the etch rate. The ion beam continuously impacts the substrate to bombard the material on the substrate to form etching.

As shown in fig. 1, in the present embodiment, the grid is composed of three metal sheets 3 (thickness d), the metal sheets 3 are usually high temperature resistant metal Mo, and ceramic members (length t) are provided between the metal sheets 3 to insulate them from each other; each sheet of metal is connected to a different voltage potential.

The middle of each metal sheet 3 is provided with densely arranged honeycomb-shaped holes 31; the sizes, arrangements, layouts, etc. may be different, and are usually in a close-packed structure with equal diameter and areas, as shown in fig. 2.

Ions formed by the grid mesh of the structure in an accelerated mode can form approximately parallel plasma beams with high energy for etching the surface of a wafer.

The first embodiment is as follows:

the utility model provides an adjust hole butyl of ion etching homogeneity, includes cap portion 1 and pole portion 2, the one end and the cap portion 1 fixed connection of pole portion 2, the side of pole portion 2 is provided with notch 21.

The preferred porous member in this embodiment is made of an insulating, high temperature resistant material, such as ceramic, quartz, etc.

In order to facilitate the matching with the grid mesh, the width of the notch 21 is preferably d, the height is preferably X, and the size of the rod part 2 on the hole D is smaller than that of the hole 31 of the metal sheet 3, so that the hole D can be conveniently inserted into the hole 31, and the hole D is firmly fixed on the grid mesh by means of the gravity of the hole D and the coupling of the thickness of the notch 21 and the thickness of the metal sheet 3, and further the ion concentration at the position and the periphery is small.

Wherein the cross-section of the shaft 2 is preferably circular, i.e. the shaft 2 is cylindrical as a whole, so long as the radius of the shaft 2 is smaller than the radius of the hole 31 of the metal sheet 3.

As shown in fig. 3 and 4, the hole d has a non-axisymmetric structure, i.e. the rod part 2 is connected to the cap part 1 at an off-center position, preferably the cross-section of the cap part 1 is circular, i.e. the rod part 2 is connected to the cap part 1 at a non-center position, more preferably the rod part 2 is connected to the edge of the cap part 1, and the radius of the cap part 1 is R, which is larger than the radius R of the hole 31 of the metal sheet 3, so as to ensure that the corresponding hole 31 can be covered.

Of course, the cap 1 may have other shapes, such as a triangle, a quadrangle, an irregular shape, etc.

The cap 1 in this embodiment is sized to cover the holes 31 of one mesh or the holes 31 of a plurality of adjacent meshes.

Example two:

as shown in fig. 4, in the present embodiment, the rod portion 2 has a plurality of notches 21, the plurality of notches 21 are uniformly distributed along the length direction of the rod portion 2, and the distance between two adjacent notches 21 is equal to the distance between two adjacent metal sheets 3 of the grid, that is, the distance t between two adjacent notches 21 is equal to the length of the separation ceramic 4 between the metal sheets 3.

Taking the grid with three metal sheets 3 as an example, the notches 21 can be three to couple with three metal sheets 3 at the same time, so that the holes are firmly fixed on the grid, and the other technical characteristics are the same as those of the first embodiment.

As shown in fig. 5, a method for adjusting ion etching uniformity includes the following steps:

s1: etching the wafer by adopting an ion source grid mesh to obtain ion etching thickness or rate distribution data; s2: preparing an etching thickness or rate T ═ f (R/R) graph;

s3: judging whether the etching uniformity requirement is met according to the T-f (R/R) diagram;

s4: if the requirement of etching uniformity is met, the step S5 is carried out; if the requirement of etching uniformity is not met, inserting a plurality of holes at the positions of the corresponding ion source grids at the positions with higher etching thickness according to a T ═ f (R/R) diagram, and then returning to the step S1;

s5: and finishing the adjustment.

Fig. 6-9 show specific test cases performed using the above-described method.

In fig. 6, a is a graph of normalized etching thickness as a function of the distance from the center of the wafer to the edge of the wafer in the radial direction without any hole, i.e., T ═ f (R/R). As can be seen, the etching thickness of the wafer starts to increase at R/R-0.32, increases to the maximum at R/R-0.63, and then slowly decreases, and the uniformity of the etching thickness is StdD%: 3.17%, as shown in fig. 7. This indicates that the ion concentration of the etch increases rapidly starting at-0.32R/R and then slowly decreases.

Based on this situation, in the ion source grid,

1. a ceramic hole D is inserted at the position which is about 0.50 radius away from the center;

2. three ceramic hole nuts are inserted at the position which is about 0.63 radius away from the center;

3. two ceramic hole nuts are inserted at the position which is about 0.95 radius away from the center;

thus, the inserted ceramic hole packet effectively weakens the ion concentration at the position and the periphery and the corresponding etching speed, so that the etching thickness of the corresponding area is weakened, and the uniformity of the etching thickness is greatly improved, as shown by a curve B in figure 6. The uniformity of the etching thickness reached StdD% ═ 1.05%, as shown in fig. 8.

Further, in the ion source grid,

1.2.3.4. a ceramic hole D is inserted into the position which is about 0.50 radius away from the center;

5. a ceramic hole D is inserted at the position which is about 0.63 radius away from the center;

6. a ceramic hole D is inserted into the position which is about 0.95 radius away from the center;

thus, the inserted ceramic hole T effectively weakens the ion concentration at the position and the periphery and the corresponding etching speed, so that the etching thickness of the corresponding area is weakened, and the uniformity of the etching thickness is greatly improved, as shown by a curve C in figure 6. The uniformity of the etching thickness reached StdD% ═ 0.20%, as shown in fig. 9.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to those skilled in the art without departing from the principles of the present invention should also be considered as within the scope of the present invention.

Claims (8)

1. A hole T for adjusting the ion etching uniformity is characterized in that: the novel cap comprises a cap part and a rod part, wherein one end of the rod part is fixedly connected with the cap part, and a notch is formed in the side face of the rod part.

2. A hole die for adjusting ion etching uniformity according to claim 1, wherein: the stem portion is attached to the cap at a position offset from the center of the cap.

3. A hole die for adjusting ion etching uniformity according to claim 2, wherein: the width of the notch is equal to the thickness of the metal sheet of the grid mesh.

4. A hole die for ion regulating etch uniformity as recited in claim 3, wherein: the cap is sized to cover the openings of one mesh or the openings of adjacent meshes.

5. The ion adjusted etch uniformity pot of claim 4, wherein: the cross section of the cap part is circular.

6. A hole die for ion regulating etch uniformity as recited in any of claims 1-5, wherein: the rod part is provided with a plurality of notches which are uniformly distributed along the length direction of the rod part, and the distance between every two adjacent notches is equal to the distance between every two adjacent metal sheets of the grid mesh.

7. The ion adjusted etch uniformity pot of claim 6, wherein: the cap part and the rod part are made of ceramic or quartz.

8. A method for adjusting ion etching uniformity is characterized by comprising the following steps:

s1: etching the wafer by adopting an ion source grid mesh to obtain ion etching thickness or rate distribution data;

s2: preparing an etching thickness or rate T ═ f (R/R) graph;

s3: judging whether the etching uniformity requirement is met according to the T-f (R/R) diagram;

s4: if the requirement of etching uniformity is met, the step S5 is carried out; if the requirement of etching uniformity is not met, inserting a plurality of holes at the positions of the corresponding ion source grids at the positions with higher etching thickness according to a T ═ f (R/R) diagram, and then returning to the step S1;

s5: and finishing the adjustment.

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