'(' and ')' are magic characters in a regex so need to be quoted if you want a literal match for them. One way to do it is use the quote meta sequence. Consider:

use strict;
use warnings;
my $data = <<DATA;
DataAchr(9)DataBchr(9)DataC
DATA

open my $infile, '<', \$data;

while (<$infile>) {
  chomp;
  my $re = 'chr(9)';
  my @array= split(/\Q$re\E/,$_);
  print "@array\n";
}

close $infile;
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Prints:

DataA DataB DataC
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