CN101660134A - Method for improving magnetron-sputtered film thickness uniformity - Google Patents

Abstract

The invention discloses a method for improving magnetron-sputtered film thickness uniformity. An optimum correcting baffle is arranged between two planes of a substrate and a target. The centers of the substrate, the target and the correcting baffle are coaxial. A baffle theory model relatively close to actual situation is created, and baffle parameters for realizing optimum film thickness uniformity are calculated. The method reduces the deposition rate of a position close to the circle center on the substrate to a certain extent, thereby optimizing and improving the uniformity.

Description

A kind of method of improving magnetron-sputtered film thickness uniformity

Technical field

The present invention relates to the electric mechanical technical field, be specifically related to a kind of method of improving magnetron-sputtered film thickness uniformity.

Background technology

In various sputter coating technology, magnetron sputtering technique is one of most important technology, and in order to prepare the even and consistent in batches good film of big area, a large amount of researchists adopts measures such as optimizing target-substrate distance, change substrate mode of motion, implementation film thickness monitoring.Multi-work-station magnetron sputtering plating instrument since its speed than adjustable and make a plurality of substrates simultaneously, efficient improves greatly, is more and more paid attention to and uses.

X.Q.Meng research group derives the film thickness distribution formula in order to reach preparation large area uniform film purpose theoretically according to actual magnetron sputtering situation.Formula according to them can get: substrate is far away more apart from target, and the homogeneity of film is good more.Generally when distance L＜0.8R2 (R2 is the external diameter of etching ring on the target), the homogeneity of film is very good.Simultaneously, the author also points out: do not have close relation between the energy of the projectile of bombardment target and depositing of thin film speed, the homogeneity.

The argumentation of robot systems such as Fan Zhengxiu the thickness distribution of magnetron sputtering film, analyzed fixed substrate theoretically, substrate rotates and rotation adds film thickness distribution under three kinds of states of revolution, calculation result shows that film thickness distribution depends on matrix height to a great extent.Suitably regulate the distance of matrix height and target, can obtain good film uniformity.

For area vacuum sputter coating system, position film near the center of circle on the substrate is thicker usually, people such as Zhang Suhuai change the shape of target by borehole, make the sedimentation rate of target central authorities weakened, calculating and experiment confirm are opened the hole that varies in size in the middle of circular and square target, can obtain homogeneity less than 3% film, the homogeneity of film is relevant with the size of perforate and target-substrate distance.In actual plated film, sometimes target material be unsuitable in the middle of perforate, and for magnetic control sputtering system, there is tangible etching runway in target, so be impracticable by changing the method that target shape improves film uniformity in actual production.

Therefore finding a kind of film uniformity and feasible method can improved is to be necessary very much and significant.

Summary of the invention

Problem to be solved by this invention is: how a kind of method of improving magnetron-sputtered film thickness uniformity is provided, and this method can calculate the optimum parameter of revising baffle plate, and the film uniformity of magnetron sputtering coating system preparation will be arrived below 3%.

Technical problem proposed by the invention is to solve like this: a kind of method of improving magnetron-sputtered film thickness uniformity is provided, it is characterized in that, be in the middle of substrate and two planes of target the correction baffle plate to be set, substrate, target and correction baffle plate are concentric, specifically may further comprise the steps:

Step 1 is determined the relative thickness of target certain point on substrate in the planar magnetic control sputtering system device

If M is an any point on the substrate, its coordinate is (x ', y '), and ds is the small bin that M is ordered, N be in the sputter runway district a bit, its coordinate be (x, y), d σ is the small bin that N is ordered, and in the unit time, this little bin sedimentary film thickness t on ds can be formulated as:

$t=\frac{m\cos \mathrm{\θ}\cos \mathrm{\β}}{\mathrm{\π\ρ}{r}^2}=\frac{{\mathrm{mh}}^2}{\mathrm{\π\ρ}{r}^4}---\left(1\right)$

Wherein, m is the total mass that little bin sputters Coating Materials in the unit time, equal the product of this sputter rate and time on the numerical value, θ is the input angle of coating materials one's share of expenses for a joint undertaking to the deposition bin, it is the angle of bin ds normal and incident atoms direction, β is the emission angle of sputtered atom, and ρ is the density of target, and r is the distance between sputter bin and the deposition bin;

Step 2 is carried out grid at substrate and is divided

Equidistantly on the substrate radius choose 16 points, under the X-Y system of coordinates, starting point is (r, 0), terminal point (0,0), the substrate rotation, circular frequency is Wz, and one-period 2 π/Wz is divided into 20 intervals, follows the trail of the position coordinates (x of each some M at each time period end ₀, y ₀);

Step 3 is carried out grid and is divided on target

For the rectangle runway, directly be divided into i * j rectangular node at two bar-shaped zones, in semi-circular zone, use radius between interior through R1 and outside semicircle between the R2 and the straight line of directions X combine division; For circular, use polar form to carry out grid and divide;

Step 4 is set up and is revised the baffle plate model

Suppose that certain point moves to M (x on the substrate ₀, y ₀), (x, y) line with M can be expressed as to put N on the target

$\frac{x^{\′}-x_0}{x-x_0}=\frac{y^{\′}-y_0}{y-y_0}=\frac{z^{\′}-z_0}{z-z_0}---\left(2\right)$

The height of z ' expression baffle plate is wherein tried to achieve the intersection point (x ', y ', z ') of straight line and baffle plane;

Step 5 is determined the shape of baffle plate

1. rectangle baffle plate

The rectangle length and width are respectively 2b and 2a, when-b＜x '＜b and-during a＜y '＜a, some P thinks that at baffle interior sputtered atom is blocked, and does not count, and when a=b, obtains the model of square baffle plate;

2. oval baffle plate

The length of long axis of ellipse and minor axis is respectively f and g, when

The time, some P when f=g, obtains the model of circular baffle plate at baffle interior;

Step 6 is found the solution optimum baffle plate parameter

Homogeneity for film thickness distribution is expressed by using general formula (3):

$G=\frac{\mathrm{Max}-\mathrm{Min}}{\mathrm{Max}+\mathrm{Min}}---\left(3\right)$

Wherein, Max and Min represent the minimum and maximum value of film thickness on the substrate respectively, and under every kind of baffle plate parameter of being come out by top Model Calculation, film gauge uniformity deviation G is exactly optimum baffle plate parameter when wherein G gets minimum value.

This method is used for the planar magnetic control sputtering filming equipment, the substrate rotation, and the shape of baffle plate can be chosen regular shapes and irregularly shaped such as circle, ellipse, rectangle.The shape of target mainly comprises circle, rectangle, and target material can be chosen monometallic target, alloy target material and compound target.

Beneficial effect of the present invention: revise baffle plate by in the middle of substrate and two planes of negative electrode target, increasing, reduced the sedimentation rate of close circle centre position on the substrate to a certain extent, thereby realized inhomogeneity optimization and improvement.Set up comparatively near the baffle plate theoretical model of practical situation, calculated and realize the best inhomogeneity baffle plate parameter of thickness.Use the film gauge uniformity of present method preparation preferably can reach below 3%.

Description of drawings

Fig. 1 is a planar magnetic control sputtering coating system baffle plate model diagram, and wherein 1 is substrate, the 2nd, and baffle plate, the 3rd, target, substrate, target, baffle plate center are coaxial.

Fig. 2 is rectangular target grid division figure, and wherein L is the length of bar shaped runway, and R1 and R2 represent the inside and outside radius of annulus runway respectively.

Fig. 3 is the circular synoptic diagram.

Fig. 4 be when not adding baffle plate the magnetron sputtering deposition film thickness distribution with the variation diagram of target-substrate distance.

Fig. 5 is when selecting square baffle plate, the baffle plate deposit film thickness distribution figure of the different length of sides.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described:

Of the present invention a kind of by using the method that baffle plate improves the magnetron sputtering film gauge uniformity of revising, the step below adopting:

Step (1) is determined the planar rectangular target magnetic control sputtering system relative thickness of certain point in the plane

P is an any point on the substrate, and its coordinate is (x ', y ').Ds is the small bin that P is ordered.Q be in the sputter runway district a bit, its coordinate is that (x, y), d σ is the small bin that Q is ordered.In unit time, this little bin sedimentary film thickness on ds can be used formula ^[9]Be expressed as

$t=\frac{m\cos \mathrm{\θ}\cos \mathrm{\β}}{\mathrm{\π\ρ}{r}^2}=\frac{{\mathrm{mh}}^2}{\mathrm{\π\ρ}{r}^4}---\left(1\right)$

M is the total mass that little bin sputters Coating Materials in the unit time, equals the product of this sputter rate and time on the numerical value.θ is the input angle of coating materials one's share of expenses for a joint undertaking to the deposition bin.Be the angle of bin ds normal and incident atoms direction, β is the emission angle of sputtered atom, and ρ is the density of target, and r is the distance between sputter bin and the deposition bin.

The on-chip grid of step (2) is divided

Equidistantly on the substrate radius choose 16 points, under the X-Y system of coordinates, starting point is (r, 0), terminal point (0,0).Substrate rotation, circular frequency are Wz, and one-period 2 π/Wz is divided into 20 intervals, follow the trail of the position coordinates (x of each some M at each time period end ₀, y ₀).

Grid on step (3) target is divided

Only occur on the runway because the etching of magnetron sputtering is approximate, the sputter runway of rectangular target as shown in Figure 2, the method of dividing grid for rectangle runway zone is as follows, two bar-shaped zones can directly be divided into i * j rectangular node, for semi-circular zone, use radius between R1 and R2 semicircle and the straight line of directions X combine division.The sputter runway of circular as shown in Figure 3, grid divide to use polar form.The correction baffle plate model that step (4) increases

Suppose that certain point moves to M (x on the substrate ₀, y ₀), (x, y) line with M can be expressed as to put N on the target

$\frac{x^{\′}-x_0}{x-x_0}=\frac{y^{\′}-y_0}{y-y_0}=\frac{z^{\′}-z_0}{z-z_0}---\left(2\right)$

The height of z ' expression baffle plate wherein can be in the hope of the intersection point of straight line and baffle plane (x ', y ', z ')

Step (5) is determined the shape of baffle plate

Modal baffle shapes is divided into rectangle and oval two kinds, and the computational algorithm under two kinds of shapes is as follows:

1. rectangle baffle plate

The rectangle length and width are respectively 2b and 2a, when-b＜x '＜b and-during a＜y '＜a, some P thinks that at baffle interior sputtered atom is blocked, and does not count, and when a=b, obtains the model of square baffle plate.As Fig. 5, the baffle plate deposit film thickness distribution figure of the different length of sides, the magnetron sputtering deposition film thickness distribution is with the variation diagram of target-substrate distance as shown in Figure 4 when not adding baffle plate.

2. oval baffle plate

The length of long axis of ellipse and minor axis is respectively f and g.

When

The time, some P when f=g, obtains the model of circular baffle plate at baffle interior.

Step 6, find the solution optimum baffle plate parameter

Homogeneity for film thickness distribution can be expressed by using general formula (3):

$G=\frac{\mathrm{Max}-\mathrm{Min}}{\mathrm{Max}+\mathrm{Min}}---\left(3\right)$

Wherein, Max and Min represent the minimum and maximum value of film thickness on the substrate respectively.Under every kind of baffle plate parameter of being come out by top Model Calculation, film gauge uniformity deviation G is exactly optimum baffle plate parameter when wherein G gets minimum value.

With the rectangular target is example, and the length and width of choosing target are respectively 250mm and 50mm, and the diameter of substrate is 150mm.Target-substrate distance is 100mm.In Fig. 2, the runway bar length of rectangular target is 200mm, two semicircle zones of runway, and roundlet radius R 1 is 10mm, great circle radius R 2 is 20mm.

Algorithm by above-mentioned model calculates, and obtains following result:

When (1) not using baffle plate, film uniformity reaches 8%.

When (2) using the rectangle baffle plate, the wide 20mm of baffle plate, long 60mm, during height 34mm, average reaches minimum value 2.92%.

When (3) using oval baffle plate, baffle plate major axis 96mm, minor axis 20mm, during height 27mm, average reaches minimum value 3.73%.

Claims (1)

1, a kind of method of improving magnetron-sputtered film thickness uniformity is characterized in that, is in the middle of substrate and two planes of target the correction baffle plate to be set, and substrate, target and correction baffle plate center are coaxial, specifically may further comprise the steps:

Step 1 is determined the relative thickness of target certain point on substrate in the planar magnetic control sputtering system device

If M is an any point on the substrate, its coordinate is (x ', y '), and ds is the small bin that M is ordered, N be in the sputter runway district a bit, its coordinate be (x, y), d σ is the small bin that N is ordered, and in the unit time, this little bin sedimentary film thickness t on ds can be formulated as:

$t=\frac{m\cos \mathrm{\θ}\cos \mathrm{\β}}{\mathrm{\π\ρ}{r}^2}=\frac{{\mathrm{mh}}^2}{{\mathrm{\π\ρr}}^4}---\left(1\right)$

Wherein, m is the total mass that little bin sputters Coating Materials in the unit time, equal the product of this sputter rate and time on the numerical value, θ is the input angle of coating materials one's share of expenses for a joint undertaking to the deposition bin, β is the emission angle of sputtered atom, ρ is the density of target, and r is the distance between sputter bin and the deposition bin;

Step 2 is carried out grid at substrate and is divided

Equidistantly on the substrate radius choose 16 points, under the X-Y system of coordinates, starting point is (r, 0), terminal point (0,0), the substrate rotation, circular frequency is Wz, and one-period 2 π/Wz is divided into 20 intervals, follows the trail of the position coordinates (x of each some M at each time period end ₀, y ₀);

Step 3 is carried out grid and is divided on target

For the rectangle runway, directly be divided into i * j rectangular node at two bar-shaped zones, in semi-circular zone, use radius between interior through R1 and outside semicircle between the R2 and the straight line of directions X combine division; For circular, use polar form to carry out grid and divide;

Step 4 is set up and is revised the baffle plate model

Suppose that certain point moves to M (x on the substrate ₀, y ₀), (x, y) line with M can be expressed as to put N on the target

$\frac{x^{\′}-x_0}{x-x_0}=\frac{y^{\′}-y_0}{y-y_0}=\frac{z^{\′}-z_0}{z-z_0}---\left(2\right)$

The height of z ' expression baffle plate is wherein tried to achieve the intersection point (x ', y ', z ') of straight line and baffle plane;

Step 5 is determined the shape of baffle plate

1. rectangle baffle plate

The rectangle length and width are respectively 2b and 2a, when-b＜x '＜b and-during a＜y '＜a, some P thinks that at baffle interior sputtered atom is blocked, and does not count, and when a=b, obtains the model of square baffle plate;

2. oval baffle plate

The length of long axis of ellipse and minor axis is respectively f and g, when

The time, some P when f=g, obtains the model of circular baffle plate at baffle interior;

Step 6 is found the solution optimum baffle plate parameter

Homogeneity for film thickness distribution is expressed by using general formula (3):

$G=\frac{\mathrm{Max}-\mathrm{Min}}{\mathrm{Max}-\mathrm{Min}}---\left(3\right)$

Wherein, Max and Min represent the minimum and maximum value of film thickness on the substrate respectively, and under every kind of baffle plate parameter of being come out by top Model Calculation, film gauge uniformity deviation G is exactly optimum baffle plate parameter when wherein G gets minimum value.

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