Method for improving epitaxial surface resistivity test by improving pretreatment

Abstract

The invention relates to a method for improving an epitaxial surface resistivity test by improving pretreatment, which belongs to the technical field of silicon wafer processing, and comprises the following operation steps of: 1, cleaning the front and back surfaces of an epitaxial wafer after an epitaxial process is carried out through an epitaxial furnace by adopting an HF solution, then cleaning the epitaxial wafer by using UPW ultrapure water, and then introducing N2 to blow-dry the epitaxial wafer; and a natural oxide film, surface particles and the like on the surface of the epitaxial wafer are cleaned. And 2, carrying out dry oxidation on the cleaned epitaxial wafer through an oxidation furnace. And 3, after the epitaxial wafer is subjected to the pretreatment oxidation film growing process, epitaxial surface resistivity testing is carried out, and an SPV surface photovoltage method is adopted in the epitaxial surface resistivity testing. The test of one piece is predicted to be about 15 minutes, and the test result is relatively stable and accurate. The device has the advantages of convenient operation, time and labor saving and good quality stability. The epitaxial wafer subjected to dry oxidation treatment is used for measuring the surface resistivity, so that the measurement time is shortened, and the data is relatively stable and accurate.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer processing, and in particular to a method for improving epitaxial surface resistivity testing by improving pre-treatment. Background Art

[0002] During the epitaxial surface resistivity measurement process, it was found that the stability of the resistivity test was easily affected by the incomplete cleaning of the natural oxide layer on the surface of the epitaxial wafer by the cleaning machine during the epitaxial surface resistivity monitoring process. The epitaxial surface resistivity measurement machine QC2500e takes about 30 minutes per piece for the pre-treatment of the long oxide film. In addition, the entire measurement process takes about 45 minutes to measure an epitaxial wafer. This is also a bottleneck in terms of production capacity for epitaxial monitoring quality. Summary of the invention

[0003] The present invention mainly solves the deficiencies in the prior art and provides a method for improving the epitaxial surface resistivity test by improving the pre-treatment, which has the advantages of convenient operation, time saving, labor saving and good quality stability. The surface resistivity of the epitaxial wafer after dry oxidation treatment is measured, which shortens the measurement time and the data is relatively stable and accurate.

[0004] The above technical problems of the present invention are mainly solved by the following technical solutions: A method for improving epitaxial surface resistivity testing by improving pre-treatment comprises the following steps: Step 1: After the epitaxial process in the epitaxial furnace, the front and back sides of the epitaxial wafer are first cleaned with HF solution, then cleaned with UPW ultrapure water, and then blown dry with N2. The natural oxide film and some surface particles on the surface of the epitaxial wafer are cleaned.

[0005] Step 2: The cleaned epitaxial wafer is dry oxidized in an oxidation furnace.

[0006] Step 3: After the epitaxial wafer is pre-treated and the oxide film is grown, the epitaxial surface resistivity test is carried out. The epitaxial surface resistivity test adopts the SPV surface photovoltage method. It is estimated that the test of one wafer takes about 15 minutes, and the test results are relatively stable and accurate.

[0007] Preferably, the concentration of HF solution is 1%, the temperature is 25 degrees, the HF solution cleaning time is 15 seconds, the UPW ultrapure water cleaning time is 30 seconds, and the N2 drying time is 25 seconds.

[0008] Preferably, after UPW ultrapure water cleaning, wait for 1 second before N2 drying.

[0009] Preferably, the silicon wafer is placed in a quartz boat, the quartz boat is placed in a quartz tube, the quartz tube is located in a heated oxidation furnace, high-purity dry oxygen is injected through the injection port, and the heated oxidation furnace provides a high-temperature environment, and then the oxygen reacts chemically with the surface of the silicon wafer to form a dense oxide film.

[0010] Preferably, the temperature in the oxidation furnace is 900-1000°C and maintained for 3 hours.

[0011] Preferably, the epitaxial wafer is dry oxidized to grow a dense and uniform oxide film of about 50 Å, and the time for growing the oxide film is 3 minutes.

[0012] Preferably, charges are applied to the oxide film on the surface of the silicon wafer to form a stable reaction layer, so that the majority carriers go through a process from accumulation to depletion and then to inversion. The depth of the depletion layer is then calculated, and the surface resistivity of the epitaxial layer is converted through the relationship between light and the depth of the depletion layer.

[0013] The present invention can achieve the following effects: The present invention provides a method for improving epitaxial surface resistivity testing by improving pre-treatment, which has the advantages of convenient operation, time saving, labor saving and good quality stability compared with the prior art. The surface resistivity of the epitaxial wafer after dry oxidation treatment is measured, which shortens the measurement time and the data is relatively stable and accurate. DETAILED DESCRIPTION

[0014] The technical solution of the invention is further specifically described below through embodiments.

[0015] Embodiment: A method for improving epitaxial surface resistivity testing by improving pre-treatment, comprising the following steps: Step 1: After the epitaxial wafer has been subjected to the epitaxial process in the epitaxial furnace, the front and back sides of the epitaxial wafer are first cleaned with HF solution, then cleaned with UPW ultrapure water, and then blown dry with N2.

[0016] The concentration of HF solution is 1%, the temperature is 25 degrees, and the HF solution cleaning time is 15 seconds; the UPW ultrapure water cleaning time is 30 seconds. After UPW ultrapure water cleaning, wait for 1 second before N2 drying, and the N2 drying time is 25 seconds.

[0017] Step 2: The cleaned epitaxial wafer is dry oxidized in an oxidation furnace. First, the silicon wafer is placed in a quartz boat, which is placed in a quartz tube, which is located in a heated oxidation furnace. High-purity dry oxygen is injected into the injection port, and then the heated oxidation furnace provides a high temperature environment of 900-1000°C. Then, oxygen and the surface of the silicon wafer form a dense oxide film through chemical reaction.

[0018] The epitaxial wafer is dry oxidized to grow a dense and uniform oxide film of about 50A, and the time for growing the oxide film is 3 minutes.

[0019] Step 3: After the epitaxial wafer is pre-treated and the oxide film is grown, the epitaxial surface resistivity test is performed. The epitaxial surface resistivity test uses the SPV surface photovoltage method, which spreads charges on the oxide film on the surface of the silicon wafer to form a stable reaction layer, so that the majority of carriers go from accumulation to depletion and then to inversion, and then calculate the depth of the depletion layer. The surface resistivity of the epitaxial layer is converted through the relationship between light and the depth of the depletion layer.

[0020] In summary, the method of improving the epitaxial surface resistivity test by improving the pretreatment has the advantages of convenient operation, time saving, labor saving and good quality stability. The surface resistivity of the epitaxial wafer after dry oxidation treatment is measured, which shortens the measurement time and the data is relatively stable and accurate.

[0021] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A method for improving epitaxial surface resistivity testing by improving pre-treatment, characterized in that The steps are as follows: Step 1: After the epitaxial wafer has been subjected to the epitaxial process in the epitaxial furnace, the front and back sides of the epitaxial wafer are first cleaned with HF solution, then cleaned with UPW ultrapure water, and then blown dry with N2; Step 2: The cleaned epitaxial wafer is dry oxidized in an oxidation furnace; Step 3: After the epitaxial wafer is pre-treated and the oxide film is grown, the epitaxial surface resistivity test is performed. The epitaxial surface resistivity test adopts the SPV surface photovoltage method.

2. The method for improving epitaxial surface resistivity testing by improving pre-treatment according to claim 1, characterized in that: The concentration of HF solution is 1%, the temperature is 25 degrees, the HF solution cleaning time is 15s; the UPW ultrapure water cleaning time is 30s, and the N2 drying time is 25s.

3. The method for improving epitaxial surface resistivity testing by improving pre-treatment according to claim 2, characterized in that: After cleaning with UPW ultrapure water, wait for 1 second before drying with N2.

4. The method for improving epitaxial surface resistivity testing by improving pre-treatment according to claim 1, characterized in that: The silicon wafer is placed in a quartz boat, the quartz boat is placed in a quartz tube, the quartz tube is located in a heated oxidation furnace, high-purity dry oxygen is injected into the injection port, and the heated oxidation furnace provides a high-temperature environment. Then, the oxygen reacts chemically with the surface of the silicon wafer to form a dense oxide film.

5. The method for improving epitaxial surface resistivity testing by improving pre-treatment according to claim 4, characterized in that: The temperature in the oxidation furnace is 900-1000°C and is kept warm for 3 hours.

6. The method for improving epitaxial surface resistivity testing by improving pre-treatment according to claim 5, characterized in that: The epitaxial wafer is dry oxidized to grow a dense and uniform oxide film of about 50A, and the time for growing the oxide film is 3 minutes.

7. The method for improving epitaxial surface resistivity testing by improving pre-treatment according to claim 1, characterized in that: Charges are applied to the oxide film on the surface of the silicon wafer to form a stable reaction layer, causing the majority carriers to accumulate, deplete, and then invert. The depth of the depletion layer is then calculated, and the surface resistivity of the epitaxial layer is converted through the relationship between light and the depth of the depletion layer.