阅读说明：本技术 一种提高薄膜沉积均匀性的方法 (method for improving film deposition uniformity ) 是由 陈飞 于 2019-10-14 设计创作，主要内容包括：本发明提供一种提高薄膜沉积均匀性的方法,属于半导体制造技术领域,方法包括：据需要沉积的薄膜厚度预先设定一温度上限值和一温度下限值,控制沉积温度于温度上限值和温度下限值之间以预设的温度变化速率做周期性变化；上述技术方案有益效果是：使得半导体基板的边缘位置与中心位置薄膜沉积的平均速度趋近于相等,达到提高薄膜沉积厚度的均匀性的效果,提升半导体基板的良率。(The invention provides a method for improving the deposition uniformity of a film, belonging to the technical field of semiconductor manufacturing and comprising the following steps: presetting a temperature upper limit value and a temperature lower limit value according to the thickness of a film to be deposited, and controlling the deposition temperature to periodically change at a preset temperature change rate between the temperature upper limit value and the temperature lower limit value; the beneficial effects of the above technical scheme are: the average speed of the film deposition at the edge position and the center position of the semiconductor substrate is approximately equal, the effect of improving the uniformity of the film deposition thickness is achieved, and the yield of the semiconductor substrate is improved.)

1. a method for improving film deposition uniformity is applied to a high-temperature furnace tube film deposition machine and is characterized in that a temperature upper limit value and a temperature lower limit value are preset according to the thickness of a film to be deposited, and the deposition temperature is controlled to be periodically changed at a preset temperature change rate between the temperature upper limit value and the temperature lower limit value in the whole film deposition process.

2. The method of claim 1, wherein the film thickness, the upper temperature limit, the lower temperature limit, and the temperature change rate satisfy the following equations:

Wherein the content of the first and second substances,

Y is used to represent the film thickness;

N is used for representing the periodically-changed period number;

T_maxfor representing the upper temperature limit;

T_minFor representing the lower temperature limit value;

Δ T is used to represent the rate of change of temperature;

R_maxFor indicating the temperature T_maxthe corresponding film growth rate;

R_minFor indicating the temperature T_minThe corresponding film growth rate.

3. the method according to claim 1, wherein the upper temperature limit is selected from a range of 700 ℃ to 800 ℃.

4. The method according to claim 1, wherein the lower temperature limit is selected from a range of 650 ℃ to 750 ℃.

5. the method of claim 1, wherein the rate of temperature change is selected from a range of 3 ℃ to 5 ℃ per minute.

6. The method of claim 1, wherein the deposition temperature is increased from the lower temperature limit to the upper temperature limit and then decreased to the lower temperature limit for a period, or the deposition temperature is decreased from the upper temperature limit to the lower temperature limit and then increased to the upper temperature limit for a period.

7. the method of claim 1, wherein the number of the periodic variation periods is an integer.

8. The method according to claim 2, wherein Δ T is an average value of a temperature change rate in a temperature-up phase and a temperature change rate in a temperature-down phase.

9. The method for improving film deposition uniformity of claim 8, wherein the temperature change rate in the temperature-up phase is the same as the temperature change rate in the temperature-down phase.

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to a method for improving film deposition uniformity.

Background

In a semiconductor manufacturing process, different film layers are often required to be deposited on the surface of a semiconductor substrate, a vertical furnace tube deposition process in chemical vapor deposition is most commonly used, the furnace tube deposition process is batch operation, that is, a large number of semiconductor substrates are vertically placed on a wafer boat, deposition operation is performed in the furnace tube, the semiconductor substrates on the wafer boat are arranged in the vertical direction more closely, and the vertical distance between two adjacent semiconductor substrates is usually less than 7 mm.

In the furnace tube deposition process, a wafer boat for bearing a semiconductor substrate is arranged in a reaction chamber, and a heating device is arranged around the periphery of the wafer boat to heat the reaction chamber. In the prior art, a furnace tube deposition process is performed at a constant temperature, and a relatively constant temperature value in a reaction chamber is ensured by controlling intermittent heating of a heating device. Because the semiconductor substrates on the wafer boat are arranged in the vertical direction more closely, and the size of the semiconductor substrates is larger and larger, in the process of film deposition, due to the effect of heat radiation, the temperature of the edge position of the semiconductor substrate close to the heating device is higher, the temperature of the center position of the semiconductor substrate far away from the heating device is lower, and the deposition speed of the film is positively correlated with the temperature, so that the thickness uniformity of the film deposited at the center position and the edge position of the semiconductor substrate can be obviously different, the uniformity of the film is a key factor influencing chip manufacturing, the uniformity difference can cause that the key sizes of the center area and the edge area of the semiconductor substrate are inconsistent in subsequent etching processes, and the yield of the semiconductor substrate is reduced.

Disclosure of Invention

According to the above problems of the prior art, a method and a deposition apparatus for improving the uniformity of film deposition are provided, which control the deposition temperature to change periodically so that the average deposition speeds of the films at the edge and the center of the semiconductor substrate are approximately equal to each other, thereby improving the uniformity of the film deposition thickness.

The technical scheme specifically comprises the following steps:

a method for improving film deposition uniformity is applied to a high-temperature furnace tube film deposition machine and is characterized in that a temperature upper limit value and a temperature lower limit value are preset according to the thickness of a film to be deposited, and the deposition temperature is controlled to be periodically changed at a preset temperature change rate between the temperature upper limit value and the temperature lower limit value in the whole film deposition process.

Preferably, wherein the film thickness, the upper temperature limit value, the lower temperature limit value, and the temperature change rate satisfy the following formula:

wherein the content of the first and second substances,

Y is used to represent the film thickness;

N is used for representing the periodically-changed period number;

T_maxfor representingthe upper limit value of the temperature;

T_minFor representing the lower temperature limit value;

Δ T is used to represent the rate of change of temperature;

R_maxfor indicating the temperature T_maxThe corresponding film growth rate;

R_minfor indicating the temperature T_minThe corresponding film growth rate.

Preferably, wherein the upper temperature limit is selected in the range of 700 ℃ to 800 ℃.

preferably, wherein the lower temperature limit is selected in the range of 650 ℃ to 750 ℃.

Preferably, wherein the rate of temperature change is selected in the range of 3 ℃ to 5 ℃ per minute.

Preferably, the deposition temperature is increased from the lower temperature limit value to the upper temperature limit value and then decreased to the lower temperature limit value for one cycle, or the deposition temperature is decreased from the upper temperature limit value to the lower temperature limit value and then increased to the upper temperature limit value for one cycle.

Preferably, wherein the period of the periodic variation is an integer.

Preferably, Δ T is an average value of the temperature change rate in the temperature rising phase and the temperature change rate in the temperature falling phase.

Preferably, the temperature change rate of the temperature rising phase is the same as the temperature change rate of the temperature falling phase.

The beneficial effects of the above technical scheme are that:

the method for improving the film deposition uniformity is characterized in that the deposition temperature of a deposition machine is controlled to be changed periodically, so that the temperature of the edge position of the semiconductor substrate is higher than the temperature of the central position in the temperature rising process, and the temperature of the edge position of the semiconductor substrate is lower than the temperature of the central position in the temperature falling process, so that the average speed of film deposition of the edge position and the central position of the semiconductor substrate is approximately equal in the whole deposition process, the effect of improving the film deposition thickness uniformity is achieved, and the yield of the semiconductor substrate is improved.

Drawings

FIG. 1 is a schematic flow chart illustrating a method for improving the uniformity of film deposition in a furnace according to the present invention;

FIG. 2 is a schematic diagram of deposition temperature of a high temperature furnace thin film deposition machine in the prior art;

FIG. 3 is a schematic view showing the uniformity of the thickness of a thin film deposited on the surface of a wafer when the high temperature furnace thin film deposition machine is at the deposition temperature shown in FIG. 2 in the prior art;

FIG. 4 is a schematic diagram of the deposition temperature of a high temperature furnace thin film deposition machine according to the present invention;

FIG. 5 is a schematic diagram of the uniformity of the thickness of a thin film deposited on the surface of a wafer when the high temperature furnace thin film deposition apparatus is at the deposition temperature shown in FIG. 4.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.

A method for improving the deposition uniformity of a furnace tube film is applied to a high-temperature furnace tube film deposition machine, as shown in FIG. 1, wherein a temperature upper limit value and a temperature lower limit value are preset according to the thickness of a film to be deposited, and the deposition temperature is controlled to periodically change at a preset temperature change rate between the temperature upper limit value and the temperature lower limit value in the whole film deposition process.

as shown in fig. 2, in the prior art, a plurality of working modes are set in a high temperature furnace tube film deposition machine, where different working modes correspond to different deposition temperatures, but in the same working mode, the deposition temperature inside the deposition machine is kept relatively constant, and since the heating method of the deposition machine is to heat the boat and the semiconductor substrate carried on the boat in the form of thermal radiation by the heating device surrounding the periphery of the boat, during the heating process of the heating device, the edge position of the semiconductor substrate is at a higher temperature due to being close to the heating device, and the temperature is faster, and the center position of the semiconductor substrate is at a lower temperature due to being far from the heating device, and the temperature is slower; the temperature nonuniformity is further aggravated by the dense arrangement of the semiconductor substrates in the vertical direction of the wafer boat, so that the deposition speed of the film at the edge position of the semiconductor substrate is higher due to higher temperature in the film deposition process; the film at the center of the semiconductor substrate has a slow deposition rate due to a low temperature, thereby resulting in a curved film surface as shown in fig. 3.

In this embodiment, as shown in fig. 4, the originally constant deposition temperature change in each operating mode of the high-temperature furnace tube thin film deposition machine is set to be a periodic change repeatedly between a predetermined upper temperature limit and a predetermined lower temperature limit; when the deposition temperature is increased from the lower temperature limit value to the upper temperature limit value, a heating device of the high-temperature furnace tube film deposition machine table is started to heat, and at the moment, the edge position of the semiconductor substrate is higher in temperature due to the fact that the edge position is close to the heating device, the temperature is increased faster, and the film deposition speed is correspondingly faster; and the central position of the semiconductor substrate far away from the heating device is slowly heated, the temperature is relatively low relative to the edge position, the deposition speed of the film at the central position of the corresponding semiconductor substrate is relatively low, and the film deposited on the semiconductor substrate shows the trend of thin middle and thick edge in the process of the deposition temperature rising.

When the deposition temperature is reduced from the upper limit value to the lower limit value, the edge position of the semiconductor substrate is close to the edge of the wafer boat, so that the heat loss speed is high, and the temperature is reduced more quickly; the heat loss rate at the center of the semiconductor substrate is much slower than that at the edge, and the temperature drop is relatively slow, so that the temperature at the edge of the semiconductor substrate is lower than that at the center during the whole process of depositing the film, and correspondingly, the deposition rate of the film is slower at the edge of the semiconductor substrate than at the center. Therefore, the thin film deposited on the semiconductor substrate shows a tendency to be thick in the middle and thin at the edges throughout the lowering of the deposition temperature.

Since the two completely opposite trends of the film deposition on the semiconductor substrate occur during the two processes of the deposition temperature rising and falling, the two trends are continuously complemented during the whole deposition process of the film, and finally the deposition results in a relatively uniform film surface as shown in fig. 5.

As a preferred embodiment, the film thickness, the upper temperature limit value, the lower temperature limit value, and the temperature change rate satisfy the following formulas:

Wherein the content of the first and second substances,

Y is used to indicate the film thickness;

N is used for representing the periodically-changed period number;

T_maxFor indicating an upper temperature limit;

T_minFor indicating a lower temperature limit;

Δ T is used to represent the rate of change of temperature;

R_maxFor indicating the temperature T_maxThe corresponding film growth rate;

R_minFor indicating the temperature T_minThe corresponding film growth rate.

Specifically, the growth rate of the film is positively correlated with the current deposition temperature, the deposition temperature T corresponds to the film growth rate R one to one under the conditions of determination of the type of the deposited film and determination of other external factors, and the corresponding film growth rate at the deposition temperature can be determined by querying corresponding data for the given corresponding deposition temperature.

In the specific implementation process, the film thickness Y is the target film deposition thickness of the wafer to be deposited, and the temperature upper limit value T_maxand a lower temperature limit T_minAnd the rate of change of temperature Δ T is determined by the operator specifically according to the actual conditions, in order to ensure the deposition effect, as a preferred embodiment, by adjusting T within the allowable range_max、T_minAnd Δ T, such that the number of cycles N is an integer value, thereby further improving the uniformity of film deposition.

as a preferred embodiment, the upper temperature limit is selected in the range of 700 ℃ to 800 ℃.

as a preferred embodiment, the lower limit of the temperature is selected in the range of 650 ℃ to 750 ℃.

Specifically, in a certain type of film deposition process, the deposition temperature should generally satisfy a predetermined temperature range, and the upper limit and the lower limit of the temperature control of the existing high-temperature furnace tube film deposition machine are 800 ℃ and 650 ℃, respectively, as a preferred embodiment, the upper limit of the deposition temperature is selected from 700 ℃ to 800 ℃, and the lower limit of the deposition temperature is selected from 650 ℃ to 750 ℃, but in the same deposition mode, it should be ensured that the selected lower limit of the deposition temperature is smaller than the upper limit of the deposition temperature, and the specific difference between the two values can be specifically determined according to a specific deposition process and by combining with the experience summarized by an operator in the actual operation process.

as a preferred embodiment, the rate of temperature change is selected in the range of 3 ℃ to 5 ℃ per minute.

In particular, the specific indication of the temperature change rate should also be specifically determined according to the specific deposition process and the experience summarized by the operator in the actual operation process, and the final aim is to improve the uniformity of the deposited film surface.

in one embodiment, the deposition temperature is increased from the lower temperature limit value to the upper temperature limit value and then decreased to the lower temperature limit value for one cycle, or the deposition temperature is decreased from the upper temperature limit value to the lower temperature limit value and then increased to the upper temperature limit value for one cycle.

As shown in FIG. 4, it is assumed that the deposition temperature of the deposition apparatus has a temperature change rate Δ T during the rising process_{Lifting of wine}The rate of change of temperature during the descent is Δ T_DescendIn the present embodiment, Δ T_{Lifting of wine}And Δ T_{Lifting of wine}the values of (a) and (b) may be the same or different, and the slope of a straight line showing a temperature rise and the slope of a straight line showing a temperature fall may be the same or different as reflected on the temperature control map. As a preferred embodiment, Δ T_{Lifting of wine}＝ΔT_descendΔ T; and at Δ T_{Lifting of wine}and Δ T_DescendIn the case of inequality, in the above formula, Δ T in the rate of change of temperature may be Δ T_{Lifting of wine}And Δ T_descendThe average of both is taken as Δ T in the calculation formula, and is specifically expressed as Δ T_{Lifting of wine}and Δ T_DescendThe difference between these can also be determined specifically based on the particular deposition process and in combination with the operator's experience summarized during actual operation.

A high temperature furnace tube film deposition machine is disclosed, wherein the device for improving the film deposition uniformity of the furnace tube is applied.

The beneficial effects of the above technical scheme are that:

The method for improving the film deposition uniformity and the deposition machine are provided, the deposition temperature of the deposition machine is controlled to be changed periodically, so that the temperature of the edge position of the semiconductor substrate is higher than the temperature of the central position in the temperature rising process, and the temperature of the edge position of the semiconductor substrate is lower than the temperature of the central position in the temperature falling process, so that the average speed of film deposition of the edge position and the central position of the semiconductor substrate is approximately equal in the whole deposition process, the effect of improving the film deposition thickness uniformity is achieved, and the yield of the semiconductor substrate is improved.

while the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.