JPH03107482A - Etching method - Google Patents

Abstract

PURPOSE:To uniformly etch a film to be etched by measuring the temp. of a substrate at plural positions along the periphery of a susceptor and controlling the flow rate of a reactive gas from each of plural gas introducing holes in accordance with the measured values. CONSTITUTION:The temps. T1-T4 of plural positions of a susceptor 4 are measured with temp. sensors 71-74 fitted to the susceptor 4 supporting a substrate W immediately before dry etching. The data are sent to a controller 9, the optimum flow rate of a reactive gas from each of gas introducing holes 21-24 is calculated from the previously inputted optimum relation between flow rate and temp. and flow rate regulating valves V1-V4 are controlled. After flows of the reactive gas are stabilized, etching is carried out. Etching accuracy in a semiconductor producing process is improved.

Description

[Detailed description of the invention] 〔overview〕 Regarding the dry etching method.

We proposed a method to control the flow rate of reactant gas from multiple inlets and the in-plane distribution of substrate temperature, with the aim of making the etching amount distribution of the film to be etched uniform.

The substrate temperature is measured at a plurality of temperature measurement points along the periphery of the susceptor that holds the substrate to be etched, and a reaction gas is introduced from a plurality of gas inlets toward each temperature measurement point. The flow rate is determined based on a predetermined relationship between the etching amount and the reaction gas flow rate and substrate temperature so that the etching amount distribution is uniform within the substrate.

[Industrial application field]

The present invention relates to a dry etching method.

Dry Etching Apparatus 1 A dry etching method in which a reactive gas is introduced into a parallel plate type apparatus, for example, and a power is applied between parallel plate electrodes to etch a film to be etched placed on one electrode plate is a semiconductor manufacturing process. It is widely used in

[Conventional technology]

The dry etching of the present invention will be explained below using the above-mentioned typical parallel plate type apparatus.

In the conventional parallel plate type apparatus, there is only one inlet for each reaction gas, and the temperature of the susceptor on which the substrate with the film to be etched is placed is controlled only by the temperature of the cooling water of the chiller flowing under the susceptor.

Further, the susceptor is a consumable item, and the etching characteristics change when replaced.

In reality, it is not easy to make the in-plane temperature of the susceptor uniform, and it changes depending on the conditions of the etching process.

In order to make the etching amount distribution of the film to be etched on the substrate uniform, it is necessary to control the flow rate of the reaction gas introduced into the apparatus and the in-plane distribution of the substrate temperature.

Furthermore, it is not sufficient that the reaction gas introduced into the apparatus be uniform; it also needs to be able to be controlled arbitrarily.

[Problem to be solved by the invention]

The present invention proposes a method of controlling the flow rate of reaction gas from a plurality of inlets and the in-plane distribution of substrate temperature, and aims to make the etching amount distribution of the film to be etched uniform.

[Means to solve the problem]

The solution to the above problem is to measure the substrate temperature at multiple temperature measurement points along the periphery of the susceptor that holds the substrate to be etched, and then introduce the reaction gas through multiple gas inlets toward each temperature measurement point. .

This is achieved by an etching method in which the flow rate of each gas inlet is determined from a predetermined relationship between the etching amount and the reaction gas flow rate and substrate temperature so that the distribution of the etching amount is uniform within the substrate.

[Effect]

In the present invention, the experimental fact that the temperature of the susceptor (substrate temperature, more specifically, the temperature of the film to be etched deposited on the substrate) and the flow rate of the reaction gas have a large relationship with the etching rate is determined in advance. Using this result, the amount of etching of the film to be etched can be determined by controlling the flow rate of the reactive gas introduced from the plurality of reactive gases = 5 inlets while monitoring the susceptor temperature at the corresponding positions of the 2 reactive gas inlets. This is to make the distribution uniform.

〔Example〕

FIG. 1 is a schematic sectional view of an apparatus illustrating an embodiment of the present invention and a block diagram illustrating its control system.

In the figure, 1 is a reaction chamber, 21 to 24 are reaction gas inlets, 3 is an exhaust port, 4 is a susceptor, and 5 is a counter electrode.

71 to 74 are reaction gas inlet ports 2 on the back side of the susceptor.
Temperature sensors are provided at corresponding positions 1 to 24, 8 is an RF power source connected to the susceptor, W is a substrate, and V1 to V4 are flow rate regulating valves.

Next, an etching method according to an embodiment will be explained step by step.

First, immediately before etching, the temperature sensors 71 to 74 provided on the susceptor 4 measure the temperatures T+, Tz, T1 . Measure T4.

The data is sent to the controller 9, which determines the optimal reaction gas flow rate from the relationship between the flow rate and temperature from each inlet, for which the optimal conditions have been entered in advance, and determines the optimal reaction gas flow rate for each flow rate adjustment valve v1~
Control v4.

Next, etching is performed while the flow of the reaction gases is stable.

If you want to continue etching the first substrate after etching is completed, repeat the above steps each time.

Perform etching at the optimum gas flow rate.

As described above, each substrate is etched under optimal conditions, so each substrate has a uniform etching amount distribution.

Next, an example of actual etching will be explained. Derivation of the optimum flow rate from each gas inlet will be explained later using FIG. 3, and only the results will be shown here.

Substrate: 5 inch Si substrate Film to be etched: 0CD (spin-on glass) film Reactive gas: CP4/C4Fll Gas pressure: 0.2 Torr 400mm per RF electric crab substrate Susceptor temperature: T? I = 20 'C Tヮ2-15 "C1 T73 = 20 °C T74 = 15 "C1 Flow rate of each gas inlet: CF4/C, FB 100/80 SC0M total amount 1
80 SCCM Gz+-523CCM.

G2□=383CCM.

Gzx = 52 SCCM.

G24 = 383CCM Etching rate: 1800 people/M Film thickness distribution after etching: ±3.0% Film thickness distribution of conventional example: ±
15.0% (when there is one gas inlet) Here, r T 7 + " T ? a is the temperature of each measurement point 71 to 74 GKI to G+4 is each gas inlet 21 to
24 gas flow rate.

FIGS. 2(1) and 2(2) are a front sectional view and a side sectional view of the apparatus used in the example.

In the figure, 1 is a reaction chamber, 21 to 24 are reaction gas inlets, and 3 is an exhaust port connected to an exhaust system.

4 is a susceptor that holds the substrate; 5 is a counter electrode connected to a ground potential; 6 is a cooling pipe; 71 to 74 are thermocouples provided at positions corresponding to the reaction gas inlets 21 to 24 on the back surface of the susceptor; is the RF power supply connected to the susceptor,
-W is a substrate on which a film to be etched is deposited.

FIGS. 3(1) to 3(3) are diagrams illustrating the optimum conditions used for etching in the example.

Figure 3 (1) shows the etching rate [! /R shows the relationship between substrate temperature.

Gas and flow rate: CF4/C4F8 100/80 S
CCM Gas Pressure: 0.2 Torr 400mm per RF electronic substrate Etched Film: For OCD film.

FIG. 3(2) shows the relationship between the etching rate E/R and the flow rate of the reaction gas.

Gas and mixing ratio: CF4/C4F8 1.0: 0
．． 8 Gas pressure: 0.2 Torr 400 W per RF electric crab substrate Film to be etched: For OCD film.

FIG. 3(3) is an enlarged view of FIG. 3(2), showing the relationship between E/R and the flow rate of the reaction gas, and using this figure, the flow rate of each gas inlet is determined.

Now, what is the temperature of each part of the susceptor?

TR+ = 20°C9 T7□-15°C1 T? 3 = 20°C1 Tq<= 15°C4 Find the flow rate of each gas inlet for the case.

■ If the CF4/C4F11 before control is 100/803CCM, and the total flow rate is 1803CCM, evenly distributed to each gas inlet (port), the flow rate G per port will be G = 180/4 = 453CCM. . In other words, since each port is 453CCM, the E/R for this flow rate is T7□ = T74 = 15°C: E/R = 1930 from the figure.
Person/M.

Ty+=T73=20°C: E/R=1740 people/M.

The distribution width of E/R is 190 people/M.

■ After control, the total flow rate becomes 1803CCM, and further increases to 15°C520°
The flow rate of each port with the same E/R for both C is Gz+
=GZ3 = 523CCM.

Gzz = Gz4 = 38 SCCM.

Therefore, E/R at this time is 1800 people/M.

The flow rate for the etching example described above was derived as described above.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to make the etching amount distribution of the film to be etched uniform by controlling the flow rate of the reaction gas from a plurality of inlets and the in-plane distribution of the substrate temperature. Ta.

As a result, the etching precision of the semiconductor manufacturing process has been improved, and the present invention can be applied to the manufacturing process of highly integrated and ultra-fine structured LSIs.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an apparatus illustrating an embodiment of the present invention and a block diagram illustrating its control system. FIGS. 2(1) and 2(2) are a front sectional view and a side sectional view of the device used in the example. Figures 3 (1) to (3) are diagrams explaining the optimum conditions used for etching in the example, and Figure 3 (1) is the erating gray) [! /R vs. substrate temperature, Figure 3 (2) shows the relationship between etching rate E/R vs. flow rate of reaction gas, Figure 3 (3).
) is an enlarged view of FIG. 3(2). In fig. 1 is a reaction chamber. 21 to 24 are reaction gas inlets (ports), respectively. 3 is an exhaust port connected to the exhaust system. 4 is a susceptor that holds the substrate. 5 is a counter electrode connected to ground potential. 6 is a cooling pipe. 71 to 74 are reaction gas inlet ports 2 on the back side of the susceptor.
Thermocouples 8 provided at corresponding positions 1 to 24 are RF power sources connected to the susceptor. 9 is the controller. W is a substrate coated with a film to be etched. ■1~v4 are flow rate adjustment valves

Claims (1)

[Claims] The substrate temperature is measured at multiple temperature measurement points along the periphery of the susceptor that holds the substrate to be etched, and the reaction gas is introduced from multiple gas inlet ports toward each temperature measurement point, and the reaction gas is An etching method characterized in that the flow rate of the etching amount is determined from a predetermined relationship between the etching amount and the reaction gas flow rate and the substrate temperature so that the distribution of the etching amount is uniform within the substrate.